JP2004311108A - Total polymer electrolyte battery and manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium ion battery using a solid electrolyte for an electrolytic layer by which the electrolytic layer is made thinner than a conventional solid electrolytic sheet, the internal resistance of the electrolytic layer is reduced, the energy density and the output density of the battery are made higher and a high output is taken out. <P>SOLUTION: The lithium ion battery meets at least one of requirements of (1) to (4) described below. (1) The particle size of a composition material for a positive pole electrode is 8 μm or less, (2) the surface roughness Ra of the positive pole electrode is 1.4 μm or less, (3) the particle size of a composition material for a negative pole electrode is 8 μm or less, and (4) the surface roughness Ra of the negative pole electrode is 1.4 μm or less. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００１７】
該表面粗さＲａの測定方法は、後述する実施例に記載の方法により行うことができるが、特にこれに制限されるものではない。実施例に記載の方法にあるように、本発明に規定するこれらの表面粗さＲａは、製造過程であれば比較的簡単に測定することができるほか、電池完成後であっても測定可能であり、ほぼ同じ結果であることから、製造段階であれ、電池完成後であれ、いずれか一方の段階だけでも測定されたＲａが上記に規定する要件を満足するものであれば、本発明の範囲に含まれるものといえる。また、電極の表面粗さは、電極に固体電解質層が接している側の表面のものである。
【００１８】
また、正極電極の構成材料の粒径とは、最大粒径のことを言い、また負極電極の構成材料の粒径も同じく最大粒径のことを言う。基本的には活物物質、導電助剤がこれらに相当するが、膜強度向上に使用される充填剤等についての最大粒径も含まれる。これら両電極の構成材料の粒径の測定方法は、後述する実施例に記載の方法により行うことができるが、特にこれに制限されるものではない。実施例に記載の方法にあるように、本発明に規定するこれら粒径は、使用原料から簡単に測定することができるほか、電池完成後であっても測定可能であり、ほぼ同じ結果であることから、製造段階（使用原料）であれ、電池完成後であれ、いずれか一方の段階だけでも、測定された粒径が上記に規定する要件を満足するものであれば、本発明の範囲に含まれるものといえる。
【００１９】
また、固体電解質層の膜厚とは、正極電極と負極電極の間に設けた固体電解質膜のトータル膜厚をいう。これら固体電解質層の膜厚の測定方法は、後述する実施例に記載の方法により行うことができるが、特にこれに制限されるものではない。実施例に記載の方法にあるように、本発明に規定する固体電解質層の膜厚は、製造過程で形成されるポリマー電解質膜ないし固体電解質層の膜厚から簡単に測定することができるほか、電池完成後であっても測定可能であり、ほぼ同じ結果であることから、製造段階であれ、電池完成後であれ、いずれか一方の段階だけでも測定された固体電解質層の膜厚が上記に規定する要件を満足するものであれば、本発明の範囲に含まれるものといえる。
【００２０】
本発明の対象となるリチウムイオン電池としては、電解質層に固体電解質を用いたリチウムイオン電池であればよく、特に制限されるべきものではない。例えば、バイポーラ型のリチウムイオン電池、バイポーラ型ではないリチウムイオン電池などが挙げられる。ただし、固体電解質層の内部抵抗低減による高出力特性等の効果が得られるのであれば、他の種類の電池に適用することを妨げるものではない。また、これらは積層型でもよいし、巻回型でもよいなど、その形態に何ら制限されるものではない。同様に１次電池でも、２次電池でも良い。好ましくはバイポーラ型のリチウムイオン二次電池である。これは、バイポーラ型のリチウムイオン二次電池では、容量、出力特性に優れた電池を構成できるためである。更に、電解質に固体電解質を用いたバイポーラ型のリチウムイオン二次電池では、液絡の問題が無いため信頼性が高く、かつ簡易な構成で出力特性に優れたバイポーラ電池を形成することができるためである。
【００２１】
以下、本発明のリチウムイオン電池の好適な態様の１つである、電解質に固体電解質を用いたバイポーラ型のリチウムイオン二次電池（以下、単にバイポーラ電池とも称する）を例にとり説明するが、本発明がこれらに制限されるべきものではないことはいうまでもない。
【００２２】
図１〜４に、バイポーラ電池の基本構成の概略を図面を用いて簡単に説明する。このうち、図１には、バイポーラ電池を構成するバイポーラ電極の構造を模式的に表わした概略断面図を示す。図２には、バイポーラ電池を構成する単電池層の構造を模式的に表わした概略断面図を示す。図３には、バイポーラ電池の全体構造を模式的に表わした概略断面図を示す。図４には、バイポーラ電池内に複数積層された単電池層が直列に接続されてなることを記号化して概念的に表わした概略図を示す。
【００２３】
図１〜４に示したように、１枚または２枚以上で構成される集電体１の片面に正極電極（正極層ともいう）２を設け、もう一方の面に負極電極（負極層ともいう）３を設けたバイポーラ電極５（図１参照のこと）を、固体電解質層４を挟み隣合うバイポーラ電極５の電極層２、３が対向するようになっている。すなわち、バイポーラ電池１１では、集電体１の片方の面上に正極層２を有し、他方の面上に負極層３を有するバイポーラ電極（電極層）５を、電解質層４を介して複数枚積層した構造の電極積層体（バイポーラ電池本体）７からなるものである。最上層と最下層の電極５ａ、５ｂは、バイポーラ電極構造ではなく集電体１（または端子板）に必要な片面のみの電極層（正極層２または負極層３）を形成した構造となっている。
【００２４】
また、こうしたバイポーラ電極５等を複数枚積層した電極積層体７の最上層と最下層の電極５ａ、５ｂは、バイポーラ電極構造でなくてもよく、集電体１（または端子板）に必要な片面のみの電極層（正極層２ないし負極層３）を配置した構造としてもよい（図３参照のこと）。また、バイポーラ電池１１では、上下両端の集電体１にそれぞれ正極および負極リード８、９が接合されている。
【００２５】
バイポーラ電極の積層回数は、所望する電圧に応じて調節する。本発明では、シート状電池の厚みを極力薄くしても十分な出力が確保できるものであるので、バイポーラ電極の積層回数を少なくしてもよい。
【００２６】
また、本発明のバイポーラ電池１１では、使用する際の外部からの衝撃、環境劣化を防止するために、電極積層体７部分を電池外装材（外装パッケージ）１０に減圧封入し、電極リード８、９を電池外装材（外装パッケージ）１０の外部に取り出した構造とするのがよい（図３、４参照のこと）。軽量化の観点からは、アルミニウム、ステンレス、ニッケル、銅などの金属（合金を含む）をポリプロピレンフィルム等の絶縁体で被覆した高分子−金属複合ラミネートフィルムなど、従来公知の電池外装材を用いて、その周辺部の一部または全部を熱融着にて接合することにより、電極積層体７を収納し減圧封入（密封）し、電極リード８、９を電池外装材１０の外部に取り出した構成とするのが好ましい。このバイポーラ電池１１の基本構成は、図４に示すように、複数積層した単電池層（単セル）６が直列に接続された構成ともいえるものである。
【００２７】
以下、本発明のバイポーラ電池の構成要素を中心に説明する。
【００２８】
［集電体］
本発明で用いることのできる集電体としては、特に制限されるものではなく、従来公知のものを利用することができる。例えば、アルミニウム箔、ステンレス（ＳＵＳ）箔、ニッケルとアルミニウムのクラッド材、銅とアルミニウムのクラッド材、ＳＵＳとアルミニウムのクラッド材あるいはこれらの金属の組み合わせのめっき材などが好ましく使える。また、金属表面に、アルミニウムを被覆させた集電体であってもよい。また、場合によっては、２つ以上の金属箔を張り合わせた集電体を用いてもよい。複合集電体を用いる場合、正極集電体の材料としては、例えば、アルミニウム、アルミニウム合金、ＳＵＳ、チタンなどの導電性金属を用いることができるが、アルミニウムが特に好ましい。一方、負極集電体の材料としては、例えば、銅、ニッケル、銀、ＳＵＳなどの導電性金属を用いることができるが、ＳＵＳ及びニッケル等が特に好ましい。また、複合集電体においては、正極集電体と負極集電体とは、互いに直接あるいは第三の材料からなる導電性を有する中間層を介して電気的に接続していれば良い。
【００２９】
複合集電体における正極集電体および負極集電体の各厚みは、通常通りでよく両集電体とも、例えば、１〜１００μｍ程度である。好ましくは集電体（複合集電体を含む）の厚さが１〜１００μｍ程度であるのが電池の薄型化の観点からは望ましい。
【００３０】
［正極電極］
ここで、正極電極の構成材料としては、正極活物質を含むものであれば良く、さらに必要に応じて、電子伝導性を高めるための導電助剤、バインダ、固体電解質、イオン伝導性を高めるための電解質支持塩などが含まれ得る。
【００３１】
正極活物質としては、遷移金属とリチウムとの複合酸化物（リチウム−遷移金属複合酸化物）を好適に使用できる。具体的には、ＬｉＭｎ_２Ｏ_４などのＬｉ・Ｍｎ系複合酸化物、ＬｉＣｏＯ_２などのＬｉ・Ｃｏ系複合酸化物、Ｌｉ_２Ｃｒ_２Ｏ_７、Ｌｉ_２ＣｒＯ_４などのＬｉ・Ｃｒ系複合酸化物など、ＬｉＮｉＯ_２などのＬｉ・Ｎｉ系複合酸化物、ＬｉＦｅＯ_２などのＬｉ・Ｆｅ系複合酸化物およびこれらの遷移金属の一部を他の元素により置換したものなどが使用できるなど、Ｌｉ金属酸化物から選択し使用するが、本発明はこれらの材料に限定されるものではない。これらリチウム−遷移金属複合酸化物は、反応性、サイクル耐久性に優れ、低コストな材料である。そのためこれらの材料を電極に用いることにより、出力特性に優れた電池を形成することができる点で有利である。この他、ＬｉＦｅＰＯ_４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；Ｖ_２Ｏ_５、ＭｎＯ_２、ＴｉＳ_２、ＭｏＳ_２、ＭｏＯ_３などの遷移金属酸化物や硫化物；ＰｂＯ_２、ＡｇＯ、ＮｉＯＯＨなどが挙げられる。
【００３２】
上記導電助剤としては、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。
【００３３】
上記バインダとしては、ポリフッ化ビニリデン（ＰＶＤＦ）、ＳＢＲ、ポリイミドなどが使用できる。ただし、これらに限られるわけではない。
【００３４】
本発明では電解質層に固体電解質を用いるため、正極電極にも固体電解質が含まれていることが望ましい。正極電極における正極活物質間の空隙に固体電解質を充填することによって、正極電極におけるイオン伝導がスムーズになり、バイポーラ型のリチウムイオン電池全体としての出力向上が図れるためである。
【００３５】
固体電解質は、イオン伝導性を有する高分子から構成されるものであり、イオン伝導性を示すのであれば材料は限定されない。好ましくは、固体電解質形成用の重合性ポリマーを熱重合、紫外線重合、放射線重合、電子線重合により架橋構造を形成することによって作製できるものが、優れた機械的強度が発現するため望ましい。かかる固体電解質形成用の重合性ポリマーとしては、分子構造中に少なくともエーテル結合を有し、また末端に重合性官能基を有している必要性がある。重合性官能基としては一般的な二重結合でよい。また、このポリマーの基本骨格となる主鎖部を３〜６官能基とし、各官能基に連結する側鎖がエーテル結合を含むランダム共重合体とし、それぞれの末端に重合性官能基として二重結合を有するコポリマーとすることもできる。この構造とすることにより重合反応を行った場合、網目状の高分子化が可能となる。また、それぞれの側鎖のランダム共重合体を、ポリエチレンオキシド、ポリプロピレンオキシドから得ることもできる。
【００３６】
上記重合性ポリマーとしては、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）、これらの共重合体（実施例参照のこと）のような公知の重合性ポリマーを使用することができる。これらＰＥＯ、ＰＰＯのようなポリアルキレンオキシド系高分子は、下記電解質支持塩をよく溶解しうる点で優れている。本発明において固体電解質は、正極電極または負極電極の少なくとも一方に含まれる。ただし、バイポーラ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。
【００３７】
電解質支持塩としては、例えば、ＬｉＰＦ_６、ＬｉＢＦ_４、ＬｉＣｌＯ_４、ＬｉＡｓＦ_６、ＬｉＴａＦ_６、ＬｉＡｌＣｌ_４、Ｌｉ_２Ｂ_１０Ｃｌ_１０等の無機酸陰イオン塩、Ｌｉ（ＣＦ_３ＳＯ_２）_２Ｎ、Ｌｉ（Ｃ_２Ｆ_５ＳＯ_２）_２Ｎ、ＬｉＣ_４Ｆ_９ＳＯ_３、ＬｉＣＦ_３ＳＯ_３、Ｌｉ（Ｃ_２Ｆ_５ＰＦ_３）等の有機酸陰イオン塩、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。
【００３８】
正極電極における、正極活物質、導電助剤、バインダ、固体電解質、電解質支持塩等の成分配合量は、電池の使用目的（出力重視、エネルギー重視など）、イオン伝導性を考慮して決定すればよい。例えば、固体電解質を例にとれば、正極電極内における固体電解質の配合量が少なすぎると、正極電極内でのイオン伝導抵抗やイオン拡散抵抗が大きくなり、電池性能が低下してしまう。一方、正極電極内における固体電解質の配合量が多すぎると、電池のエネルギー密度が低下してしまう。従って、これらの要因を考慮して、目的に合致した固体電解質量を決定する。
【００３９】
正極電極の厚さは、特に限定するものではなく、配合量について述べたように、電池の使用目的（出力重視、エネルギー重視など）、イオン伝導性を考慮して決定すべきである。一般的な正極電極の厚さは１０〜５００μｍ程度である。
【００４０】
本発明では、正極電極の構成材料の粒径が８μｍ以下、好ましくは６μｍ以下のものを使用するのが望ましい。これは、電極表面の凹凸（表面粗度）を低減し、更にバイポーラ電池の電極抵抗を低減する上で極めて有用なためである。また、一般的に利用されている平均粒径ではなく、最大粒径を規定したのは、正極電極の構成材料中に含まれる粒径の大きなものを排除することが極めて重要となるためである。これにより、上記したように、電極表面上に粒径の大きな正極電極の構成材料による凹凸が形成されるのを防止し、電解質層の薄膜化に伴う短絡の問題を効果的に防止できるものである。なお、ここでいう正極電極の構成材料としては、主に正極活物質であるが、このほかにも導電助剤が挙げられる。バインダ、固体電解質、電解質支持塩は、これら粉末の隙間を埋めるものであり、正極電極表面に凹凸を形成し、表面粗さの増大を招くものではないため、これらに関しては正極電極の構成材料の粒径の規定には含めないものとする。
【００４１】
本発明では、正極電極の表面粗さＲａが１．４μｍ以下、好ましくは１．１μｍ以下である。これによっても、電解質層の薄膜化に伴う微小短絡の問題を効果的に防止することができ、固体電解質の内部抵抗低減に寄与し得るものである。なお、電解質層に固体電解質を用いるため、液体電解質を用いる場合のように電極表面をプレスなどにより緻密化しても、電解液の内部浸透性を防止し充放電特性に影響を及ぼすような問題も無く、良好な充放電特性を発現し得るものである。なお、上記表面粗さＲａの要件を満足する場合には、例えば、正極電極の構成材料の粒径が８μｍ以下のものを使用することによっても達成することができるほか、正極電極の構成材料に粒径が８μｍを超えるものを使用することができる点で有利である。この場合、例えば、集電体の片面に正極電極（更には他面に負極電極）を形成した後、必要に応じて冷間または温間にてプレス操作を行うことで、表面粗さＲａを１．４μｍ以下に調整できる。
【００４２】
［負極電極］
負極電極（負極層）は、負極活物質を含む。この他にも、電子伝導性を高めるための導電助剤、バインダ、イオン伝導性を高めるための電解質支持塩、固体電解質などが含まれ得る。
【００４３】
本発明では、電解質層に固体電解質を用いるため、負極電極にも固体電解質が含まれていることが望ましい。負極電極における負極活物質間の空隙に固体電解質を充填することによって、負極電極におけるイオン伝導がスムーズになり、バイポーラ型のリチウムイオン電池全体としての出力向上が図れるためである。
【００４４】
負極活物質の種類や形状等以外は、基本的に「正極電極」の項で記載した内容と同様であるため、ここでは負極活物質の種類や形状等と本発明の特徴部分である負極電極の構成材料の粒径、負極電極の表面粗さＲａ以外の説明を省略する。
【００４５】
負極活物質としては、液体電解質を用いる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。具体的には、カーボン、金属化合物、金属酸化物、Ｌｉ金属化合物、Ｌｉ金属酸化物などを用いることができる。これらは１種単独で使用しても良いし、２種以上を併用して用いても良い。好ましくはカーボンもしくはリチウム−遷移金属複合酸化物である。これらは、反応性、サイクル耐久性に優れ、低コストな材料である。そのため、これらの材料を電極に用いることにより、出力特性に優れた電池を形成することができる。カーボンとしては、例えば、グラファイトカーボン、ハードカーボン、ソフトカーボンなどを用いることができる。なお、リチウム−遷移金属複合酸化物としては、例えば、Ｌｉ_４Ｔｉ_５Ｏ_１２などのリチウム−チタン複合酸化物などを用いることができる。また、金属化合物としては、ＬｉＡｌ、ＬｉＺｎ、Ｌｉ_３Ｂｉ、Ｌｉ_３Ｃｄ、Ｌｉ_３Ｓｄ、Ｌｉ_４Ｓｉ、Ｌｉ_４．４Ｐｂ、Ｌｉ_４．４Ｓｎ、Ｌｉ_０．１７Ｃ（ＬｉＣ_６）等から、金属酸化物としては、ＩｎＯ_２、ＳｉＯ、ＳｎＯ、ＳｎＯ_２、ＳｎＳＯ_４、ＺｎＯ、ＣｏＯ、ＮｉＯ、ＦｅＯ等から、Ｌｉ金属化合物としては、Ｌｉ_３ＦｅＮ_２、Ｌｉ_２．６Ｃｏ_０．４Ｎ、Ｌｉ_２．６Ｃｕ_０．４Ｎ等から、Ｌｉ金属酸化物（リチウム−遷移金属複合酸化物）としては、Ｌｉ_４Ｔｉ_５Ｏ_１２などＬｉ_ｘＴｉ_ｙＯ_ｚで表されるリチウム−チタン複合酸化物等から選択し使用することができる。
【００４６】
負極電極の構成材料の形状は、その種類等によって取り得る形状が異なり、例えば、平板状、波板状、棒状、粉末状などが挙げられるがこれらに限定されない。負極電極の構成材料の粒径ないし負極電極の表面粗さＲａの要件を満足し本発明の目的を達成し得るものであればよく、いずれの形状であれ問題なく使用できるが、好ましくは、負極電極の構成材料の種類に応じて、充放電特性などの電池特性を向上し得る最適の形状を適宜選択すればよい。
【００４７】
負極電極の構成材料のミクロ構造も、その種類等によって取り得る形状が異なり、例えば、積層状、球状、繊維状、螺旋状、フィブリル状が挙げられるがこれらに限定されない。この場合にも、負極電極の構成材料の粒径ないし負極電極の表面粗さＲａの要件を満足し本発明の目的を達成し得るものであればよく、いずれのミクロ構造であっても問題なく使用できるが、好ましくは、負極電極の構成材料の種類に応じて、充放電特性などの電池特性を向上し得る最適のミクロ構造のものを適宜選択すればよい。
【００４８】
負極電極の厚さは、特に限定するものではなく、配合量について述べたように、電池の使用目的（出力重視、エネルギー重視など）、イオン伝導性を考慮して決定すべきである。一般的な負極電極の厚さは１０〜５００μｍ程度である。
【００４９】
本発明では、負極電極の構成材料の粒径が８μｍ以下、好ましくは６μｍ以下のものを使用するのが望ましい。これは、「正極電極の構成材料の粒径」の項で説明したのと同様の理由であり、同様の効果がもたらされるため、ここでの説明は省略する。また、負極電極の構成材料に関しても「負極電極の構成材料」について説明したのと同様であるため、ここでの説明は省略する。
【００５０】
本発明では、正極電極および負極電極の構成材料の粒径が共に８μｍ以下であることがより望ましく、これら電極間に形成可能な固体電解質層のより一層の薄膜化が可能となる。
【００５１】
本発明では、負極電極の表面粗さＲａが１．４μｍ以下、好ましくは１．１μｍ以下である。これは「正極電極の表面粗さＲａ」の項で説明したのと同様の理由であり、同様の効果がもたらされ、同様に調整し得るため、ここでの説明は省略する。
【００５２】
［固体電解質層］
本発明の固体電解質層（以下、単に電解質層ともいう）を構成する固体電解質は、イオン伝導性を有する高分子から構成されるものであり、イオン伝導性を示すのであれば材料は限定されない。好ましくは、固体電解質形成用の重合性ポリマーを熱重合、紫外線重合、放射線重合、電子線重合により架橋構造を形成することによって作製できるものが、優れた機械的強度が発現するため望ましい。かかる固体電解質層を構成する固体電解質では液漏れがないので、液絡の問題が無く信頼性が高く、かつ簡易な構成で出力特性に優れたリチウムイオン電池を形成することができる。
【００５３】
上記重合性ポリマーとしては、基本的に「正極電極」の項で記載した内容と同様であるため、ここでの説明を省略する。
【００５４】
上記重合性ポリマー中には、イオン伝導性を確保するために電解質支持塩が含まれる。電解質支持塩としては、基本的に「正極電極」の項で記載した内容と同様であるため、ここでの説明を省略する。
【００５５】
固体電解質は、当該電解質層、正極電極、負極電極に含まれ得るが、同一の固体電解質を使用してもよく、それぞれ異なる固体電解質を用いてもよい。
【００５６】
上記電解質層の厚さは、正極および／または負極電極の表面性状をコントロールすることにより、従来達成困難であったレベルでの薄膜化が可能となったものであり、内部抵抗を低減させるには薄ければ薄いほど良いと言える。具体的には３０μｍ以下、好ましくは２０μｍ以下、より好ましくは５〜２０μｍ、特に５〜１５μｍの範囲である。なお、電解質層の厚さの下限値は、コンパクトな全固体高分子電池を得る上で、電解質層としての機能が確保できる範囲で極力薄くし得る値である。なお、ここでいう電解質層の厚さは、正極電極と負極電極との間に設けられる電解質層の厚さをいう。したがって、当該電解質層の形成方法によっては、厚さの同じまたは異なる複数のポリマー電解質膜を貼り合せるなどして形成されることもあり得るが、こうした場合でも上記に規定する電解質層の厚さは、これら複数のポリマー電解質膜を貼り合せるなどして形成される電解質層の厚さである。
【００５７】
ところで、現在好ましく使用される重合性ポリマーは、ＰＥＯ、ＰＰＯのようなポリエーテル系高分子である。このため、高温条件下における正極側での耐酸化性が弱い。従って、溶液系のリチウムイオン電池で一般に使用される、酸化還元電位の高い正極剤を使用する場合には、負極の容量が、高分子固体電解質層を介して対向する正極の容量より少ないことが好ましい。負極の容量が対向する正極の容量より少ないと、充電末期に正極電位が上がり過ぎることを防止できる。なお、正極および負極の容量は、正極および負極を製造する際の理論容量として、製造条件から求めることができる。完成品の容量を測定装置で直接測定してもよい。ただし、負極の容量を対向する正極の容量と比べて少ないと、負極電位が下がりすぎて電池の耐久性が損なわれる恐れがあるので充放電電圧に注意する必要がある。例えば、一つの単電池層（セル）の平均充電電圧を使用する正極活物質の酸化還元電位に対して適切な値に設定して、耐久性が低下しないように注意する。
【００５８】
［絶縁層］
絶縁層は、電池内で隣り合う集電体同士が接触したり、積層電極の端部の僅かな不ぞろいなどによる短絡が起こるのを防止する目的で、各電極の周囲に形成されてなるものである。本発明では、必要に応じて、電極の周囲に絶縁層を設けてもよい。これは、車両駆動用ないし補助用電源として利用するような場合には、たとえ固体電解質を用いて電解液による短絡（液落）を完全に防止したとしても、電池への振動や衝撃が長期にわたり負荷される。そのため、電池寿命の長期化の観点からは、絶縁層を設置することがより長期間の信頼性、安全性を確保する上で望ましく、高品質の大容量電源を提供できる点で望ましいためである。
【００５９】
該絶縁層としては、絶縁性、固体電解質の脱落に対するシール性や外部からの水分の透湿に対するシール性（密封性）、電池動作温度下での耐熱性などを有するものであればよく、例えば、エポキシ樹脂、ゴム、ポリエチレン、ポリプロピレン、ポリイミドなどが使用できるが、耐蝕性、耐薬品性、作り易さ（製膜性）、経済性などの観点からは、エポキシ樹脂が好ましい。
【００６０】
［正極および負極端子板］
正極および負極端子板は、必要に応じて使用すればよい。すなわち、バイポーラ型のリチウムイオン電池の積層（ないし巻回）構造によっては、最外部の集電体から電極端子を直接取り出しても良く、この場合には正極および負極端子板は用いなくとも良い。
【００６１】
正極および負極端子板を用いる場合には、端子としての機能を有するほか、薄型化の観点からは極力薄い方がよいが、積層されてなる電極、電解質および集電体はいずれも機械的強度が弱いため、これらを両側から挟示し支持するだけの強度を持たせることが望ましい。さらに、端子部での内部抵抗を抑える観点から、正極および負極端子板の厚さは、通常０．１〜２ｍｍ程度が望ましいといえる。
【００６２】
正極および負極端子板の材質は、通常リチウムイオン電池で用いられる材質を用いることができる。例えば、アルミニウム、銅、チタン、ニッケル、ステンレス鋼（ＳＵＳ）、これらの合金などを利用することができる。耐蝕性、作り易さ、経済性などの観点からは、アルミニウムを用いることが好ましい。
【００６３】
正極端子板と負極端子板との材質は、同一の材質を用いてもよいし、異なる材質のものを用いてもよい。さらに、これら正極および負極端子板は、材質の異なるものを多層に積層したものであってもよい。
【００６４】
正極および負極端子板は、集電体の電極形成部ないし電極形成部よりも外側に設定する折り線近傍までの範囲と同じサイズであればよい。
【００６５】
［正極および負極リード］
正極および負極リードに関しては、液体電解質を用いた溶液系のリチウムイオン電池で用いられる公知のリードを用いることができる。なお、電池外装材（電池ケース）から取り出された部分は、周辺機器や配線などに接触して漏電したりして製品（例えば、自動車部品、特に電子機器等）に影響を与えないように、耐熱絶縁性の熱収縮チューブなどにより被覆しておくのが好ましい。
【００６６】
［電池外装材（電池ケース）］
バイポーラ型に限らず、リチウムイオン電池では、使用する際の外部からの衝撃、環境劣化を防止するために、電池本体である電池積層体ないし電池巻回体全体を電池外装材ないし電池ケースに収容するのが望ましい。軽量化の観点からは、アルミニウム、ステンレス、ニッケル、銅などの金属（合金を含む）の両面をポリプロピレンフィルム等の絶縁体（好ましく耐熱性の絶縁体）で被覆した高分子−金属複合ラミネートフィルム（例えば、ポリプロピレン−アルミニウム複合ラミネートフィルム；単にアルミラミネートフィルムともいう）など、従来公知の電池外装材を用いて、その周辺部の一部または全部を熱融着にて接合することにより、電池積層体を収納し密封した構成とするのが好ましい。この場合、上記正極および負極リードは、上記熱融着部に挟まれて上記電池外装材の外部に露出される構造とすればよい。また熱伝導性に優れた高分子−金属複合ラミネートフィルムなどを用いることが、自動車の熱源から効率よく熱を伝え、電池内部を電池動作温度まですばやく加熱することができる点で好ましい。
【００６７】
また、本発明のリチウムイオン電池の用途としては、例えば、電気自動車（ＥＶ）やハイブリッド電気自動車（ＨＥＶ）や燃料電池自動車やハイブリッド燃料電池自動車などの大容量電源として、高エネルギー密度、高出力密度が求められる車両駆動用電源や補助電源に好適に利用することができる。この場合には、本発明のリチウムイオン電池を複数個接続して構成した組電池とすることが望ましい。すなわち、本発明のリチウムイオン電池を少なくとも２個以上を用いて直列および／または並列に接続して構成し構成し組電池化することにより、高容量、高出力の電池モジュールを形成することが出来る。そのため、使用目的ごとの電池容量や出力に対する要求に、比較的安価に対応することが可能になる。
【００６８】
次に、本発明に係るリチウムイオン電池の製造方法としては、上述した▲１▼〜▲４▼の要件の少なくとも１つの要件、更には固体電解質層の膜厚が２０μｍ以下との要件を満足し得る電池を提供できるものであれば、特に制限されるべきものではなく、従来公知の各種の方法を適宜利用することができる。
【００６９】
例えば、上記▲１▼および／または▲３▼の要件を満足する電池を提供するには、例えば、正極および／または負極用スラリー原料に用いる正極および／または負極活物質及び導電助剤の粒径を８μｍ以下にすればよい。
【００７０】
上記▲２▼および／または▲４▼の要件を満足する電池を提供するには、例えば、正極および／または負極電極を冷間または熱間でプレスロールしてもよいし、上記▲１▼および／または▲３▼の要件を満足する正極ないし負極用スラリー原料を用いても良い。
【００７１】
更に固体電解質層の膜厚が２０μｍ以下との要件を満足し得る電池を提供するには、正極電極表面および／または負極電極表面にポリマー電解質膜を作製した後、これらを正極電極表面および／または負極電極表面を該ポリマー電解質膜を介して貼り合わせ、且つこのときのポリマー電解質膜同士の貼合せにより形成される固体電解質層の膜厚が２０μｍ以下になるように調整すればよい。そして、膜厚２０μｍ以下の固体電解質層は、例えば、正極電極上および／または負極電極上に、ポリマー電解質膜形成用の重合性ポリマーを含有する溶液を塗布した後、透明基板を貼り付け、透明基板側から紫外線を照射した後、該透明基板を取り除くことにより作製することができる。あるいは正極電極上および／または負極電極上に、ポリマー電解質膜形成用の重合性ポリマーを含有する溶液を塗布した後、正極電極と負極電極を貼り合わせ、加熱操作により重合を行うことによっても作製することができる。
【００７２】
以下に、本発明のリチウムイオン電池の製造方法の好適な態様の１つである、電解質層に固体電解質を用いてなるバイポーラ型のリチウムイオン電池の製造方法を例にとり説明するが、本発明はこれらに何ら制限されるべきものでない。
【００７３】
（１）正極用組成物の塗布
まず、適当な集電体（正極集電体を含む）を準備する。正極用組成物は通常はスラリー（正極用スラリー）として得られ、集電体（または正極集電体）の一方の面に塗布される。
【００７４】
正極用スラリーは、正極活物質を含む溶液である。他成分として、導電助剤、バインダ、重合開始剤、固体電解質の原料である重合性ポリマーおよび電解質支持塩などが任意で含まれる。例えば、正極用スラリーは、正極活物質を含む溶剤中に重合性ポリマー、導電助剤を添加し、更に重合開始剤、電解質支持塩を添加し、ホモミキサー等で攪拌することで得られる。
【００７５】
正極活物質、導電助剤、バインダ、電解質支持塩、固体電解質の高分子原料（重合性ポリマー）に関しては、基本的に「本発明のリチウムイオン電池」の構成要件である「正極電極」の項で記載した内容と同様であるため、ここでの説明を省略する。
【００７６】
本発明では、正極電極の構成材料の粒径が８μｍ以下になるように、上記正極用スラリーの各原料（粉体に限る）に、粒径８μｍ以下のものを用いるのが望ましい。これにより、正極電極作製後にプレス操作を行わなくとも、正極電極の表面粗さＲａを１．４μｍ以下にすることができ、本発明の作用効果を達成することができるほか、工数の削減に寄与できる。
【００７７】
重合開始剤は、重合方法（熱重合法、紫外線重合法、放射線重合法、電子線重合法など）や重合させる化合物に応じて適宜選択する必要がある。例えば、紫外線重合開始剤としてベンジルジメチルケタール、熱重合開始剤としてアゾビスイソブチロニトリルなどが挙げられるが、これらに制限されるべきものではない。
【００７８】
Ｎ−メチル−２−ピロリドン（ＮＭＰ）、ｎ−ピロリドンなどのスラリー粘度調整用溶媒は、正極用スラリーの種類に応じて適宜選択する。
【００７９】
正極活物質、電解質支持塩、導電助剤の添加量は、バイポーラ電池の使用目的等に応じて調節すればよく、通常用いられる量を添加すればよい。重合開始剤の添加量は、固体電解質用の高分子原料（重合性ポリマー）に含まれる架橋性官能基の数に応じて決定される。通常は上記高分子原料に対して０．０１〜１質量％程度である。
【００８０】
（２）正極電極の形成
正極用スラリーが塗布された集電体（正極集電体を含む）を乾燥して、含まれる溶媒を除去する。それと同時に、正極用スラリーによって、熱、紫外線、放射線、電子線等により重合性ポリマーを重合（架橋）させて、集電体上に正極電極を形成する。乾燥ないし熱重合は真空乾燥機などを用いることができるなど、従来公知の装置を用いることができる。乾燥ないし熱重合の条件は塗布された正極用スラリーに応じて決定され、一義的に規定できないが、例えば、乾燥ないし熱重合条件は、通常は４０〜１５０℃で５分〜２０時間である。
【００８１】
本発明では、正極電極の表面粗さＲａが１．４μｍ以下になるように調整するのが望ましい。具体的な調整法としては、正極用スラリーの各原料（粉体に限る）に粒径８μｍ以下のものを用いることで正極電極作製終了後、特にプレス操作を行うことなく達成することができる。また、正極用スラリーの各原料（粉体に限る）に粒径８μｍを超えるものを利用する場合には、正極電極作製終了後にプレス操作を行うことにより調整することができる。プレス操作は冷間でプレスロールする方法または熱間でプレスロールする方法のいずれの方法でも良いが熱間でプレスロールする方法の場合は、電解質支持塩や重合性ポリマーが分解する温度以下（例えば、実施例３参照のこと。）が望ましい。プレス圧力は線圧で２００〜１０００ｋｇ／ｃｍで行うことが望ましい。プレス圧力が線圧で２００ｋｇ／ｃｍ未満の場合には、正極電極の構成材料の粒径等にもよるが表面粗さＲａを１．４μｍ以下にするのが困難な場合がある。一方、プレス圧力が線圧で１０００ｋｇ／ｃｍを超える場合には、集電体金属と塗布電極面の硬さが異なることによる歪が発生しヨレ等が発生するほか、正極電極中の活物質粒子等が圧潰されたり活物質粒子同士が圧着されたりして、充放電特性に影響を及ぼすおそれがある。なお、正極用スラリーの各原料（粉体に限る）に粒径８μｍ以下のものを用いる場合であっても、正極電極作製終了後に上記プレス操作を行っても良いことは言うまでもない。これにより正極電極の表面粗さをより一層小さくでき、電極間に形成可能な電解質層をより一層薄くできるためである。
【００８２】
（３）負極用組成物の塗布
集電体の正極電極が形成された面と反対側の面に、または負極集電体の一方の面に、負極活物質を含む負極用組成物（負極用スラリー）を塗布する。
【００８３】
負極用スラリーは、負極活物質を含む溶液である。他成分として、導電助剤、バインダ、重合開始剤、固体電解質の高分子原料および電解質支持塩などが任意で含まれる。使用される原料や添加量については、「（１）正極用組成物の塗布」の項での説明と同様であるため、ここでは説明を省略する。
【００８４】
また、本発明では、負極電極の構成材料の粒径が８μｍ以下になるように、負極用スラリーの各原料（粉体に限る）に粒径８μｍ以下のものを用いるのが望ましい。これも「（１）正極用組成物の塗布」の項で説明したのと同様の理由であり、同様の効果がもたらされるため、ここでの説明は省略する。
【００８５】
（４）負極電極の形成
負極用スラリーが塗布された集電体（負極集電体を含む）を乾燥して、含まれる溶媒を除去する。それと同時に、負極用スラリーによって、熱、紫外線、放射線、電子線等により重合性ポリマーを重合（架橋）させて、集電体上に負極電極を形成する。集電体（負極集電体を除く）の場合にはバイポーラ電極が完成する（図１参照のこと）。乾燥および重合装置及び条件等に関しては、「（２）正負極電極の形成」の項で説明したのと同様であるためここでの説明は省略する。
【００８６】
本発明では、負極電極の表面粗さＲａが１．４μｍ以下になるように調整するのが望ましい。負極電極の表面粗さＲａの具体的な調整法、該調整法で用いるプレス操作やプレス条件、スラリー原料に粒径８μｍ以下のものを用いる場合でもプレス操作が適用できる点等に関しては、既に「（２）正極電極の形成」の項で説明したのと同様であるため、ここでの説明は省略する。
【００８７】
また、上記「（２）正極電極の形成」の項で説明したプレス操作は、例えば、集電体の片面に正極電極を形成し、他面に負極電極を形成した後に、正極電極および負極電極をまとめて行っても良い。また、正極集電体の片面に正極電極を形成した後にプレス操作してもよいし、負極集電体の片面に負極電極を形成した後にプレス操作してもよい。さらに、正極集電体上に形成した正極電極と負極集電体上に負極電極とを貼り合せた後にまとめてプレス操作してもよいなど、該プレス操作の対象や時期については、必要に応じて適宜選択すればよい。また、プレス条件については、正極または負極電極の場合でも、正極及び負極電極をまとめて行う場合であっても、上記「（２）正極電極の形成」の項で説明した範囲内において調整することができる。
【００８８】
なお、上記（１）正極用組成物の塗布〜（４）負極電極の形成の工程は、特に順序を問わない。例えば、（３）〜（４）の工程を先に行い、その後（１）〜（２）の工程を行っても良い。また、集電体の両側に（１）と（３）の工程を同時に行い、（２）と（４）の工程を同時に行うようにしても良い。更に、（１）と（３）の工程は別々（いずれが先でも良い）に行い、次に（２）と（４）の工程を同時に行っても良いなど、工程順序は（１）〜（４）の工程順序に何ら制限されるべきものではない。
【００８９】
（５）固体電解質層（ないしポリマー電解質膜）の作製
固体電解質層（ないしポリマー電解質膜）は、例えば、固体電解質の原料高分子（重合性ポリマー）、電解質支持塩等をＮＭＰのような溶媒に溶解させて調製した溶液（「ポリマー電解質膜形成用の重合性ポリマーを含有する溶液」または単に「重合性ポリマー含有溶液」ともいう）を重合（硬化）、加熱乾燥させることによって製造される。
【００９０】
例えば、上記（１）〜（４）の工程により重合反応を終了し電極の表面粗さＲａを１．４μｍ以下にした正極電極および／または負極電極の上に、溶媒に重合性ポリマー、重合開始剤及び電解質支持塩を添加混合して調製された重合性ポリマー含有溶液を塗布し、該重合性ポリマー含有溶液と接する表面が平滑である支持体を気泡が残らないように密着させ、不活性雰囲気下、特定の膜厚を保持した状態で熱重合、紫外線重合、放射線重合または電子線重合を行い、所定の厚さの固体電解質層ないしポリマー電解質膜を作製する。重合反応終了後、正極電極および／または負極電極上の支持体を取り除き、表面にポリマー電解質膜を有する正極電極および／または負極電極をそれぞれ作製する。これらを充分乾燥後貼り合わせた際の、電極間の固体電解質層の膜厚を２０μｍ以下にするには、本工程において、例えば、スペーサなどを用いて、上記の如く特定の膜厚を保持できる状態で重合するのが望ましい。
【００９１】
また、正極電極及び負極電極表面の片方あるいは両方に前述の重合性ポリマー含有溶液を塗布し、これらを支持体で挟み込んだ後、熱重合や放射線重合、電子線重合することができるが、この場合も固体電解質層の膜厚は２０μｍ以下にするのが望ましく、スペーサなどを用いて制御できる。
【００９２】
あるいは、別途、電極間に積層される電解質層ないしポリマー電解質膜を準備してもよい。この場合には、例えば、上記ポリマー電解質膜形成用の重合性ポリマーを含有する溶液を、上記支持体ないし適当な離型フィルム上に塗布し、別の支持体ないし離型フィルムを気泡が残らないように密着させ、特定の膜厚を保持した状態で熱重合、紫外線重合、放射線重合または電子線重合を行い、所定の厚さの固体電解質層ないしポリマー電解質膜を作製することもできる。この場合も固体電解質層の膜厚は２０μｍ以下にするのが望ましく、スペーサなどを用いて制御できる。
【００９３】
上記支持体としては、重合方法により適宜最適なものを選択すればよい。例えば、紫外線を照射して重合を行う場合には、紫外線透過性を有する支持体、例えば、透明基板を用いる必要がある。また、加熱して熱重合反応させる場合には、加熱温度下で耐熱性を有する支持体であればよく、耐熱性の樹脂フィルムや樹脂シートなどを用いることができる。また、電子線や放射線を照射して重合を行う場合には、これら電子線や放射線は透過性が強いため、電極側から照射しても目的を達成することができるため、支持体は、特定の膜厚を保持（支持）できるものであればよい。
【００９４】
上記離型フィルムは、製造過程で８０℃程度に加熱されることもありえるため、当該温度程度での十分な耐熱性を有し、さらにポリマー電解質膜形成用の重合性ポリマーを含有する溶液との反応性がなく、製造過程で剥離し除去する必要上、離型性に優れたものを用いるのが望ましく、例えば、ポリエチレンテレフタレート（ＰＥＴ）、ポリプロピレンフィルムなどを使用することができるが、これらに制限されるべきものではない。また、これらのフィルムに適当な離型剤、例えば、シリコーン系離型剤などを塗布乾燥してなるものを用いることができる。
【００９５】
重合装置に関しては、重合方法により従来公知の重合装置を選択すればよく、例えば、熱重合反応させるには、真空乾燥機（真空オーブン）などを用いることができる。重合条件に関しても、重合方法ごとに最適な条件を適宜選択して行えばよく、例えば、熱重合反応の条件は上記溶液に応じて決定され、一義的に規定できないが、通常は３０〜１１０℃で０．５〜１２時間である。
【００９６】
また、上記熱重合以外の重合方法、例えば、紫外線重合開始剤を用いて紫外線重合反応させる場合には、紫外線透過性のギャップに上記溶液を流し込み、乾燥及び光重合ができるような紫外線照射装置を用いて紫外線を照射して、溶液内の固体電解質の高分子原料（重合性ポリマー）を光重合反応（架橋反応）を進行させて製膜するとよい。ただし、この方法に限定されないことは勿論である。重合開始剤の種類に応じて、放射線重合、電子線重合、熱重合などを使いわける。
【００９７】
なお、得られる固体電解質層の幅は、バイポーラ電極の集電体の電極形成部サイズよりも若干小さくすることが多いが、特に制限されるものではない。
【００９８】
上記溶液の組成成分やその配合量などについては、使用目的に応じて適宜決定されるべきものである。
【００９９】
（６）バイポーラ電極と固体電解質層（ないしポリマー電解質膜）との積層
▲１▼電解質層（ないしポリマー電解質膜）が一面または両面に形成されたバイポーラ電極の場合には、高真空下で十分加熱乾燥してから、電解質層（ないしポリマー電解質膜）が形成された電極を適当なサイズに複数個切りだし、切り出された電極を直接貼り合わせたものを複数層積層することにより、バイポーラ電池本体（電極積層体）を作製する。
【０１００】
▲２▼別々にバイポーラ電極と電解質層（ないしポリマー電解質膜）を作製した場合には、高真空下で十分加熱乾燥してから、バイポーラ電極と電解質層（ないしポリマー電解質膜）をそれぞれを適当なサイズに複数個切りだす。切りだされたバイポーラ電極と電解質層（ないしポリマー電解質膜）とを所定数貼り合わせたものを複数層積層することにより、バイポーラ電池本体（電極積層体）を作製する。
【０１０１】
上記電極積層体の積層数は、バイポーラ電池に求める電池特性を考慮して決定される。また、正極側の最外層には、集電体上に正極層のみを形成した電極を配置する。負極側の最外層には、集電体上に負極層のみを形成した電極を配置する。
【０１０２】
また、バイポーラ電極と電解質層（ないしポリマー電解質膜）とを積層、あるいは電解質層（ないしポリマー電解質膜）が形成された電極を積層させてバイポーラ電池を得る段階は、電池内部に水分等が混入するのを防止する観点から、不活性雰囲気下で行うことが好ましい。例えば、アルゴン雰囲気下や窒素雰囲気下でバイポーラ電池を作製するとよい。
【０１０３】
（７）絶縁層の形成
本発明では、例えば、電極積層体の電極形成部の周囲を、所定の幅でエポキシ樹脂（前駆体溶液）等に浸漬または樹脂を注入ないし含浸する。いずれの場合にも、事前に集電体を離型性マスキング材等を用いてマスキング処理しておく。その後エポキシ樹脂を硬化させて、絶縁部を形成し、その後、マスキング材を剥がせばよい。
【０１０４】
（８）リード端子の接続
バイポーラ電池本体（電池積層体）の両最外層の電子伝導性層上にそれぞれ、正極端子板、負極端子板を設置し、該正極端子板、負極端子板に、さらに正極リード、負極リードを接合（電気的に接続）する（図３参照のこと。）。正極リードおよび負極リードの接合方法としては、接合温度の低い超音波溶接等が好適に利用し得るものであるが、これに限定されるべきものではなく、従来公知の接合方法を適宜利用することができる。
【０１０５】
（９）パッキング（電池の完成）
最後に、電池積層体全体を、外部からの衝撃、環境劣化を防止するために、電池外装材ないし電池ケースで封止し、バイポーラ電池を完成させる。封止の際には、正極リード、負極リードの一部を電池外部に取り出す。電池外装材（電池ケース）の材質は、内面がポリプロピレンフィルム等の絶縁体で被覆された金属（アルミニウム、ステンレス、ニッケル、銅など）が好適である。
【０１０６】
尚、上記（１）〜（９）の工程を通して説明した例を以下に示す。
【０１０７】
まず、アルミニウムとＳＵＳからなる複合集電体のアルミニウム側に正極用スラリーを塗布し硬化させて正極電極を作製し、裏側のＳＵＳ側に負極用スラリーを塗布し硬化させて負極電極を作製した後、それぞれの電極表面に重合性ポリマー含有溶液を塗布し硬化させてポリマー電解質膜を作製した一体型電極を複数個作製する。これらを十分乾燥した後、複数層積層することによりバイポーラ型電池を作製することができる。この場合積層したバイポーラ電池本体（電極積層体）の最外部の集電体から電極端子（リード端子）を取り出し、バイポーラ電池本体を、例えば、アルミラミネートフィルムでシールすることができる。また、必要に応じて、正極及び負極電極の単電極を作製し、ポリマー電解質膜を介して前述のバイポーラ型電池の最外部の集電体として用いることもできる（図３の最上層と最下層の電極５ａ、５ｂ参照のこと）。
【０１０８】
【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。
【０１０９】
尚、以下の実施例および比較例では、特に断らない限り、正極電極用重合性ポリマー、負極電極用重合性ポリマー、電解質膜用重合性ポリマーとして、下記式に示すポリエチレンオキシド−ポリプロピレン共重合体（共重合比ｍ：ｎ＝５：１、重量平均分子量が８０００〜９０００のもの）を用いた。
【０１１０】
【化１】

【０１１１】
また、正極電極および負極電極の表面粗さＲａの測定方法は、いずれも以下に示す方法により行った。
【０１１２】
表面粗さＲａの測定は、接触式表面粗さ計（サーフコム１４００Ａ 株式会社東京精機）を用いて測定した。正極電極及び負極電極作製後、約２０ｍｍ□に切断し表面粗さを測定することにより、接触式表面粗さ計付属のパソコンで自動的にＲａの値が得られる。また正極電極と負極電極の間に固体電解質膜を積層して全固体ポリマー電池を作製し、電池性能評価（充放電評価）を行った後、各電極を剥離し正極電極表面または負極電極表面の表面粗さを測定することができる。また剥離困難な場合は積層されている電池断面を光学顕微鏡やＳＥＭで撮影し、正極電極及び負極電極の表面形状からＲａを求めることができる。
【０１１３】
また、正極電極および負極電極の構成材料の粒径の測定方法は、いずれも以下に示す方法により行った。
【０１１４】
使用原料の粒径の測定方法としては、レーザー回折散乱法（島津製作所ＳＡＬＤ−２０００Ａ）により測定できる。また、電池作製後の各電極の構成材料の粒径の測定方法としては、ミクロトームにより断面方向のサンプリングを実施した後、ＴＥＭによる観察で測定することができる。
【０１１５】
また、固体電解質層の膜厚の測定方法は、いずれも以下に示す方法により行った。
【０１１６】
固体電解質膜単独で作製した場合は、ダイヤルゲージ等の通常の膜厚計で測定することができる。電池作製後の固体電解質膜の測定方法としては、切断面を光学顕微鏡により観察し、膜厚を測定することができる。
【０１１７】
実施例１
正極電極の作製は、正極活物質として平均粒径４μｍでかつ最大粒径６μｍ以下のＬｉＭｎ_２Ｏ_４を２６質量部、導電助剤として平均粒径５００ｎｍでかつ最大粒径３μｍ以下のアセチレンブラックを８質量部、更に正極電極用重合性ポリマーとして前述のポリエチレンオキシド−ポリプロピレン共重合体１００質量部に対して０．１質量部の熱重合開始剤ＡＩＢＮ（アゾビスイソブチルニトリル）と電解質支持塩Ｌｉ（Ｃ_２Ｆ_５ＳＯ_２）_２Ｎ ３１質量部をｎ−ピロリドン溶媒に溶解した重合性ポリマーを含む溶液６６質量部をそれぞれ計量し、ホモミキサーで混合分散して正極スラリーを作製した。該正極スラリーをＡｌ集電体（正極活物質電極集電体）上にコーターで塗布し、１２０℃のオーブンで熱重合した。これを９０℃で真空乾燥し、厚さ３０μｍの正極電極を作製した。得られた正極電極の表面粗さＲａは１．１μｍであった。
【０１１８】
負極電極の作製は、負極活物質として平均粒径６μｍでかつ最大粒径８μｍ以下のＬｉ_４Ｔｉ_５Ｏ_１２を２６質量部、導電助剤として平均粒径５００ｎｍでかつ粒径３μｍ以下のアセチレンブラックを８質量部、更に負極電極用重合性ポリマーとして前述のポリエチレンオキシド−ポリプロピレン共重合体１００質量部に対して０．１質量部の熱重合開始剤ＡＩＢＮ（アゾビスイソブチルニトリル）と電解質支持塩Ｌｉ（Ｃ_２Ｆ_５ＳＯ_２）_２Ｎ ３１質量部をｎ−ピロリドン溶媒に溶解した重合性ポリマーを含む溶液６６質量部をそれぞれ計量しホモミキサーで混合分散して負極スラリーを作製した。該負極スラリーをＳＵＳ集電体（負極集電体）上にコーターで塗布し、１２０℃のオーブンで熱重合し、更にこれを９０℃で真空乾燥し、厚さ３５μｍの負極電極を作製した。得られた負極電極の表面粗さＲａは１．４μｍであった。
【０１１９】
ポリマー電解質膜の作製は、前述の電解質膜用重合性ポリマーとしてポリエチレンオキシド−ポリプロピレン共重合体１００質量部に対し、ｎ−ピロリドン溶媒２０質量部に０．１質量部の紫外線重合開始剤ＢＤＫ（ベンジルジメチルケタール）と４８質量部の電解質支持塩Ｌｉ（Ｃ_２Ｆ_５ＳＯ_２）_２Ｎを溶解したものを添加混合して電解質膜形成用溶液とした。該電解質膜形成用溶液を前記正極電極の上に約８μｍの厚さ（乾燥厚み）になるよう塗布し、この上に予めシリコーン系離型剤を塗布乾燥した約３０μｍの厚さのポリプロピレンフィルムを離型剤塗布面を内側にして重ね合わせ、紫外線を２０分間照射しポリマーの重合を行った。硬化後（重合終了後）、ポリプロピレンフィルムを取り除いた後、これを９０℃で真空乾燥し、正極電極の上にポリマー電解質膜を作製した。
【０１２０】
同じように前記負極電極の上に上記電解質膜形成用溶液を約７μｍの厚さ（乾燥厚み）になるよう塗布し、この上に予めシリコーン系離型剤を塗布乾燥した約３０μｍの厚さのポリプロピレンフィルムを離型剤塗布面を内側にして重ね合わせ、紫外線を２０分間照射しポリマーの重合を行った。重合終了後（硬化後）、ポリプロピレンフィルムを取り除いた後、これを９０℃で真空乾燥し、負極電極の上にポリマー電解質膜を作製した。
【０１２１】
これらの正極電極及び負極電極を５０ｍｍ×８０ｍｍに大きさにそれぞれ切り取り、ポリマー電解質膜を形成した面をそれぞれ内側にして張り合わせ、実施例１の全固体高分子電池を作製した。
【０１２２】
また、全固体高分子電池作製後にも各電極の構成材料の粒径および各電極の表面粗さＲａおよび固体電解質層（２つのポリマー電解質膜を貼り合せて構成されたもの）の膜厚を上記測定方法により求めた結果、正極電極の構成材料の粒径は６μｍ以下であり、負極電極の構成材料の粒径は８μｍ以下であった。また、正極電極の表面粗さはＲａは１．１μｍであり、負極電極の表面粗さはＲａは１．４μｍであり、固体電解質層の膜厚は１５μｍであった。
【０１２３】
実施例２
正極電極の作製は、正極活物質として粒径８μｍ以下（８μｍメッシュスルー（パス）サイズ）のＬｉＭｎ_２Ｏ_４を用いた以外は、実施例１と同じ方法で正極電極を作製した。負極電極の作製は、負極活物質として粒径８μｍ以下（８μｍメッシュスルー（パス）サイズ）のＬｉ_４Ｔｉ_５Ｏ_１２のものを用いた以外は、実施例１と同じ方法で負極電極を作製した。
【０１２４】
この正極電極及び負極電極をロールプレスを用いて８００ｋｇ／ｃｍの線圧でプレスし、表面粗さＲａが１．３μｍの正極電極及び負極電極を作製した。
【０１２５】
ポリマー電解質膜の作製は、前述の電解質膜用重合性ポリマーとしてポリエチレンオキシド−ポリプロピレン共重合体１００質量部に対し、ｎ−ピロリドン溶媒２０質量部に０．１質量部の紫外線重合開始剤ＢＤＫ（ベンジルジメチルケタール）と４８質量部の電解質支持塩Ｌｉ（Ｃ_２Ｆ_５ＳＯ_２）_２Ｎを溶解したものを添加混合して電解質膜形成用溶液とした。該電解質膜形成用溶液を前記正極電極の上に約１０μｍの厚さ（乾燥厚み）になるよう塗布し、この上に予めシリコーン系離型剤を塗布乾燥した約３０μｍの厚さのポリプロピレンフィルムを離型剤塗布面を内側にして重ね合わせ、紫外線を２０分間照射しポリマーの重合を行った。硬化後（重合終了後）、ポリプロピレンフィルムを取り除いた後、これを９０℃で真空乾燥し、正極電極の上にポリマー電解質膜を作製した。
【０１２６】
同じように前記負極電極の上に上記電解質膜形成用溶液を約５μｍの厚さ（乾燥厚み）になるよう塗布し、この上に予めシリコーン系離型剤を塗布乾燥した約３０μｍの厚さのポリプロピレンフィルムを離型剤塗布面を内側にして重ね合わせ、紫外線を２０分間照射しポリマーの重合を行った。硬化後（重合終了後）、ポリプロピレンフィルムを取り除いた後、これを９０℃で真空乾燥し、負極電極の上にポリマー電解質膜を作製した。
【０１２７】
これらの正極電極及び負極電極を５０ｍｍ×８０ｍｍに大きさにそれぞれ切り取り、ポリマー電解質膜を形成した面をそれぞれ内側にして張り合わせ、実施例２の全固体高分子電池を作製した。
【０１２８】
また、全固体高分子電池作製後にも各電極の構成材料の粒径および各電極の表面粗さＲａおよび固体電解質層（２つのポリマー電解質膜を貼り合せて構成されたもの）の膜厚を上記測定方法により求めた結果、負極電極の構成材料の粒径は８μｍ以下であり、負極電極の構成材料の粒径は８μｍ以下であった。また、正極電極の表面粗さはＲａは１．３μｍであり、負極電極の表面粗さはＲａは１．３μｍであり、固体電解質層の膜厚は１５μｍであった。
【０１２９】
実施例３
実施例２で作製した正極電極及び負極電極を、１４０℃に加熱したロールプレスを用いて４００ｋｇ／ｃｍの線圧でプレスし、表面粗さＲａが１．４μｍの正極電極及び負極電極を作製した。
【０１３０】
ポリマー電解質膜の作製は、前述の電解質膜用重合性ポリマーとしてポリエチレンオキシド−ポリプロピレン共重合体１００質量部に対し、ｎ−ピロリドン溶媒２０質量部に０．１質量部の紫外線重合開始剤ＢＤＫ（ベンジルジメチルケタール）と４８質量部の電解質支持塩Ｌｉ（Ｃ_２Ｆ_５ＳＯ_２）_２Ｎを溶解したものを添加混合して電解質膜形成用溶液とした。該電解質膜形成用溶液を前記正極電極の上に約１０μｍの厚さ（乾燥厚み）になるよう塗布し、この上に予めシリコーン系離型剤を塗布乾燥した約３０μｍの厚さのポリプロピレンフィルムを離型剤塗布面を内側にして重ね合わせ、紫外線を２０分間照射しポリマーの重合を行った。硬化後（重合終了後）、ポリプロピレンフィルムを取り除いた後、これを９０℃で真空乾燥し、正極電極の上にポリマー電解質膜を作製した。
【０１３１】
同じように前記負極電極の上に上記電解質膜形成用溶液を約５μｍの厚さ（乾燥厚み）になるよう塗布し、この上に予めシリコーン系離型剤を塗布乾燥した約３０μｍの厚さのポリプロピレンフィルムを離型剤塗布面を内側にして重ね合わせ、紫外線を２０分間照射しポリマーの重合を行った。硬化後（重合終了後）、ポリプロピレンフィルムを取り除いた後、これを９０℃で真空乾燥し、負極電極の上にポリマー電解質膜を作製した。
【０１３２】
これらの正極電極及び負極電極を５０ｍｍ×８０ｍｍに大きさにそれぞれ切り取り、ポリマー電解質膜を形成した面をそれぞれ内側にして張り合わせ、実施例３の全固体高分子電池を作製した。
【０１３３】
また、全固体高分子電池作製後にも各電極の構成材料の粒径および各電極の表面粗さＲａおよび固体電解質層（２つのポリマー電解質膜を貼り合せて構成されたもの）の膜厚を上記測定方法により求めた結果、負極電極の構成材料の粒径は８μｍ以下であり、負極電極の構成材料の粒径は８μｍ以下であった。また、正極電極の表面粗さはＲａは１．４μｍであり、負極電極の表面粗さはＲａは１．４μｍであり、固体電解質層の膜厚は１５μｍであった。
【０１３４】
実施例４
アルミニウムとＳＵＳからなる複合集電体（厚さ６０μｍ）のアルミニウム側に実施例１の正極電極を作製し、裏側のＳＵＳ側に実施例１の負極電極を作製した。その上に実施例１のポリマー電解質膜を正極電極及び負極電極の上に形成した。
【０１３５】
この一体型電極を５枚作製し、これらを積層した。さらに最外部の電極として実施例１と同様にして得られたポリマー電解質膜を有する正極電極及び負極電極をポリマー電解質膜を形成した面をそれぞれ内側にして張り合わせて６セル構成とする実施例４のバイポーラ型電池を試作した（図３参照のこと）。
【０１３６】
なお、バイポーラ型電池作製後の各電極の構成材料の粒径および各電極の表面粗さＲａおよび固体電解質層（２つのポリマー電解質膜を貼り合せて構成されたもの）の膜厚の測定は実施例１と同様であるので省略した。
【０１３７】
比較例１
正極電極の作製は、正極活物質として平均粒径９μｍでかつ最大粒径１１μｍ以下のＬｉＭｎ_２Ｏ_４を２６質量部、導電助剤として平均粒径５００ｎｍでかつ粒径３μｍ以下のアセチレンブラックを８質量部、更に正極電極用重合性ポリマーとして前述のポリエチレンオキシド−ポリプロピレン共重合体１００質量部に対して０．１質量部の熱重合開始剤ＡＩＢＮと電解質支持塩Ｌｉ（Ｃ_２Ｆ_５ＳＯ_２）_２Ｎ ３１質量部をｎ−ピロリドン溶媒に溶解した重合性ポリマーを含む溶液６６質量部をそれぞれ計量しホモミキサーで混合分散して正極スラリーを作製した。該正極スラリーをＡｌ集電体（正極活物質電極集電体）上にコーターで塗布し、１２０℃のオーブンで熱重合した。これを９０℃で真空乾燥し、厚さ３０μｍの正極電極を作製した。得られた正極電極の表面粗さＲａは１．８μｍであった。
【０１３８】
負極電極の作製は、負極活物質として平均粒径９μｍでかつ粒径１１μｍ以下のＬｉ_４Ｔｉ_５Ｏ_１２を２６質量部、導電助剤として平均粒径５００ｎｍでかつ粒径３ｎｍ以下のアセチレンブラックを８質量部、更に負極電極用重合性ポリマーとして前述のポリエチレンオキシド−ポリプロピレン共重合体１００質量部に対して０．１質量部の熱重合開始剤ＡＩＢＮと電解質支持塩Ｌｉ（Ｃ_２Ｆ_５ＳＯ_２）_２Ｎ３１質量部をｎ−ピロリドン溶媒に溶解した重合性ポリマーを含む溶液６６質量部をそれぞれ計量しホモミキサーで混合分散して負極スラリーを作製した。該負極スラリーをＳＵＳ集電体（負極集電体）上にコーターで塗布し、１２０℃のオーブンで熱重合し、更にこれを９０℃で真空乾燥し、厚さ３５μｍの負極電極を作製した。得られた負極電極の表面粗さＲａは１．８μｍであった。
【０１３９】
ポリマー電解質膜の作製は、前述の電解質膜用重合性ポリマーとしてポリエチレンオキシド−ポリプロピレン共重合体１００質量部に対し、ｎ−ピロリドン溶媒２０質量部に０．１質量部の紫外線重合開始剤ＢＤＫと４８質量部の電解質支持塩Ｌｉ（Ｃ_２Ｆ_５ＳＯ_２）_２Ｎを溶解し、さらにポリビニルアルコールを０．１質量部を添加混合して電解質膜形成用溶液とした。該電解質膜形成用溶液を前記正極電極の上に約１０μｍの厚さ（乾燥厚み）になるよう塗布し、この上に予めシリコーン系離型剤を塗布乾燥した約３０μｍの厚さのポリプロピレンフィルムを離型剤塗布面を内側にして重ね合わせ、紫外線を２０分間照射しポリマーの重合を行った。硬化後（重合終了後）、ポリプロピレンフィルムを取り除いた後、これを９０℃で真空乾燥し、正極電極の上にポリマー電解質膜を作製した。
【０１４０】
同じように上記電解質膜形成用溶液を前記負極電極の上に約５μｍの厚さ（乾燥厚み）になるよう塗布し、この上に予めシリコーン系離型剤を塗布乾燥した約３０μｍの厚さのポリプロピレンフィルムを離型剤塗布面を内側にして重ね合わせ、紫外線を２０分間照射しポリマーの重合を行った。硬化後（重合終了後）、ポリプロピレンフィルムを取り除いた後、これを９０℃で真空乾燥し、負極電極の上にポリマー電解質膜を作製した。
【０１４１】
これらの正極電極及び負極電極を５０ｍｍ×８０ｍｍに大きさにそれぞれ切り取り、ポリマー電解質膜を形成した面をそれぞれ内側にして張り合わせ、比較例１の全固体高分子電池を作製した。
【０１４２】
また、全固体高分子電池作製後にも各電極の構成材料の粒径および各電極の表面粗さＲａおよび固体電解質層（２つのポリマー電解質膜を貼り合せて構成されたもの）の膜厚を上記測定方法により求めた結果、負極電極の構成材料の粒径は１１μｍ以下であり、負極電極の構成材料の粒径は１１μｍ以下であった。また、正極電極の表面粗さはＲａは１．８μｍであり、負極電極の表面粗さはＲａは１．８μｍであり、固体電解質層の膜厚は１５μｍであった。
【０１４３】
比較例２
正極電極の作製は、正極活物質として平均粒径９μｍでかつ最大粒径１１μｍ以下のＬｉＭｎ_２Ｏ_４を２６質量部、導電助剤として平均粒径５００ｎｍでかつ粒径３μｍ以下のアセチレンブラックを８質量部、更に正極電極用重合性ポリマーとして前述のポリエチレンオキシド−ポリプロピレン共重合体１００質量部に対して０．１質量部の熱重合開始剤ＡＩＢＮと電解質支持塩Ｌｉ（Ｃ_２Ｆ_５ＳＯ_２）_２Ｎ ３１質量部をｎ−ピロリドン溶媒に溶解した重合性ポリマーを含む溶液６６質量部をそれぞれ計量しホモミキサーで混合分散して正極スラリーを作製した。該正極スラリーをＡｌ集電体（正極活物質電極集電体）上にコーターで塗布し、１２０℃のオーブンで熱重合した。これを９０℃で真空乾燥し、厚さ３０μｍの正極電極を作製した。得られた正極電極の表面粗さＲａは１．８μｍであった。
【０１４４】
負極電極の作製は、負極活物質として平均粒径９μｍでかつ粒径１１μｍ以下のＬｉ_４Ｔｉ_５Ｏ_１２を２６質量部、導電助剤として平均粒径５００ｎｍでかつ粒径３ｎｍ以下のアセチレンブラックを８質量部、更に負極電極用重合性ポリマーとして前述のポリエチレンオキシド−ポリプロピレン共重合体１００質量部に対して０．１質量部の熱重合開始剤ＡＩＢＮと電解質支持塩Ｌｉ（Ｃ_２Ｆ_５ＳＯ_２）_２Ｎ３１質量部をｎ−ピロリドン溶媒に溶解した重合性ポリマーを含む溶液６６質量部をそれぞれ計量しホモミキサーで混合分散して負極スラリーを作製した。該負極スラリーをＳＵＳ集電体（負極集電体）上にコーターで塗布し、１２０℃のオーブンで熱重合し、更にこれを９０℃で真空乾燥し、厚さ３５μｍの負極電極を作製した。得られた負極電極の表面粗さＲａは１．８μｍであった。
【０１４５】
ポリマー電解質膜の作製は、前述の電解質膜用重合性ポリマーとしてポリエチレンオキシド−ポリプロピレン共重合体１００質量部に対し、ｎ−ピロリドン溶媒２０質量部に０．１質量部の紫外線重合開始剤ＢＤＫと４８質量部の電解質支持塩Ｌｉ（Ｃ_２Ｆ_５ＳＯ_２）_２Ｎを溶解し、さらにポリビニルアルコールを０．１質量部を添加混合して電解質膜形成用溶液とした。該電解質膜形成用溶液を前記正極電極の上に約５０μｍの厚さ（乾燥厚み）になるよう塗布し、この上に予めシリコーン系離型剤を塗布乾燥した約３０μｍの厚さのポリプロピレンフィルムを離型剤塗布面を内側にして重ね合わせ、紫外線を２０分間照射しポリマーの重合を行った。硬化後（重合終了後）、ポリプロピレンフィルムを取り除いた後、これを９０℃で真空乾燥し、正極電極の上にポリマー電解質膜を作製した。
【０１４６】
同じように上記電解質膜形成用溶液を前記負極電極の上に約５０μｍの厚さ（乾燥厚み）になるよう塗布し、この上に予めシリコーン系離型剤を塗布乾燥した約３０μｍの厚さのポリプロピレンフィルムを離型剤塗布面を内側にして重ね合わせ、紫外線を２０分間照射しポリマーの重合を行った。硬化後（重合終了後）、ポリプロピレンフィルムを取り除いた後、これを９０℃で真空乾燥し、負極電極の上にポリマー電解質膜を作製した。
【０１４７】
これらの正極電極及び負極電極を５０ｍｍ×８０ｍｍに大きさにそれぞれ切り取り、ポリマー電解質膜を形成した面をそれぞれ内側にして張り合わせ、比較例２の全固体高分子電池を作製した。
【０１４８】
また、全固体高分子電池作製後にも各電極の構成材料の粒径および各電極の表面粗さＲａおよび固体電解質層（２つのポリマー電解質膜を貼り合せて構成されたもの）の膜厚を上記測定方法により求めた結果、負極電極の構成材料の粒径は１１μｍ以下であり、負極電極の構成材料の粒径は１１μｍ以下であった。また、正極電極の表面粗さはＲａは１．８μｍであり、負極電極の表面粗さはＲａは１．８μｍであり、固体電解質層の膜厚は１００μｍであった。
【０１４９】
＜評価結果＞
実施例１〜４および比較例１〜２の全固体高分子電池またはバイポーラ型電池の性能評価は、各活物質量から計算した電気量５Ｃでの放電率で行った。また、充電後の待機の状態での電圧の変化（電圧低下１０％以上／分）から短絡の有無を見た。
【０１５０】
［充放電の試験方法］
２０℃において、７０ｍＡの定電流で２．７５Ｖまで充電し、１０分間待機後ついで７０ｍＡの定電流で１．５Ｖまで放電させ、充電容量に対する放電容量の比率を求め、放電率とした。
【０１５１】
結果を表１に示す。
【０１５２】
【表１】

【０１５３】
表中の評価基準は以下の通りである。
【０１５４】
○：電圧低下１％未満／分
△：電圧低下１％以上／分〜電圧低下１０％未満／分
×：電圧低下１０％以上／分
【図面の簡単な説明】
【図１】本発明のバイポーラ電池を構成するバイポーラ電極の基本構造を模式的に表わした断面概略図である。
【図２】本発明のバイポーラ電池を構成する単電池層（単セル）の基本構造を模式的に表わした断面概略図である。
【図３】本発明のバイポーラ電池の基本構造を模式的に表わした断面概略図である。
【図４】本発明のバイポーラ電池の基本構成を模式的に表わしてなる概略図である。
【図５】ＪＩＳ Ｂ ０６０１−１９９４で定義される上記の数式１及びこれによって求められる表面粗さＲａを図解した図面である。
【符号の説明】
１…集電体（金属箔）、 ２…正極層（正極電極）、
３…負極層（負極電極）、 ４…固体電解質層（電解質膜）、
５…バイポーラ電極、
５ａ…集電体の必要な片面のみに正極層を配置した電極、
５ｂ…集電体の必要な片面のみに負極層を配置した電極、
６…単電池層（単セル）、 ７…電極積層体、
８…正極リード、 ９…負極リード、
１０…電池外装材、 １１…バイポーラ電池。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a lithium ion battery using a solid electrolyte (all solid polymer) for an electrolyte layer.
[0002]
[Prior art]
In the preparation of a printing plate precursor using photopolymerization, when a photopolymerization initiator generates active radicals by exposure to a laser or the like to cause addition polymerization of an ethylenically unsaturated compound, polymerization is likely to be inhibited by oxygen. For this reason, various measures have been taken such as providing a protective layer having excellent oxygen barrier properties on the photopolymerized layer before light irradiation. Water-soluble polymers such as polyvinyl alcohol and polyvinylpyrrolidone are known as materials constituting such a protective layer having excellent oxygen barrier properties (for example, see Patent Document 1).
[0003]
Further, lithium ion secondary batteries capable of achieving high energy density and high output density have been developed as large-capacity power supplies for electric vehicles and the like. The basic structure of a lithium ion secondary battery is a positive electrode in which a positive electrode active material such as lithium cobalt oxide and a conductive additive such as acetylene black are applied to an aluminum current collector using a binder, and carbon fine particles are used as a binder for the copper current collector. The negative electrode applied by using is placed via a polyolefin-based porous membrane separator, and LiPF ₆ It is filled with a non-aqueous electrolytic solution (liquid electrolyte) including the above. When applied to an electric vehicle or the like, unit cells (cells) having this configuration are connected in series, a battery module unit, and modules are connected in series to form an assembled battery.
[0004]
From the viewpoint of the energy density and the output density of the battery, it is desired to improve the connection resistance, space, and weight of the connection between cells and between modules. Recently, there has been proposed a bipolar battery employing a bipolar electrode unit that can reduce the resistance of the connection between cells and can be expected to be compact. For example, as a bipolar battery, an electrode plate in which a first set having one or two or more bipolar electrode units connected in series and a second set having the same number of bipolar electrode units as the first set are connected to terminal electrodes. The composite current collectors of the at least one bipolar electrode unit included in the first set and the bipolar electrode unit of the second set in a mirror image relationship with each other are connected in parallel so as to be in a mirror image relationship with each other as a center. A sheet battery that is directly electrically connected by a lead wire has been proposed (for example, see Patent Document 2). According to this, even if a bipolar electrode unit having a variation in charge / discharge capacity is used as a bipolar battery, a sheet battery having good discharge capacity and charge / discharge cycle characteristics can be provided. When a separator is used between the positive electrode active material layer and the negative electrode active material layer, the inside of the sheet battery needs to be filled with a liquid electrolyte. It is preferred that a solid electrolyte be used because it becomes a short circuit between the active material layers and causes a short circuit phenomenon.
[0005]
Further, as a bipolar battery, a positive electrode active material layer is formed on a positive electrode current collector layer of a composite current collector in which one surface is a positive electrode current collector layer and the other surface is a negative electrode current collector layer. There has been proposed a sheet battery which has a bipolar electrode unit having a negative electrode active material layer on a negative electrode current collector layer and uses a solid electrolyte as an electrolyte (for example, see Patent Document 3). According to this, by using a solid electrolyte as a bipolar battery, since the respective tips of the positive electrode active material layer and the negative electrode active material layer of the bipolar electrode unit are electrically insulated by vacuum or gas, The self-discharge between the two layers is prevented, and a safety battery with improved safety compared to a liquid electrolyte can be provided.
[0006]
[Patent Document 1]
JP 2001-22079 A
[Patent Document 2]
JP-A-2000-195495
[Patent Document 3]
JP 2000-100471 A
[0007]
[Problems to be solved by the invention]
However, in such a conventional technique, for example, in the case of the conventional technique as shown in Patent Document 1, a protective layer made of a water-soluble polymer such as polyvinyl alcohol or polyvinylpyrrolidone is added before light irradiation. When trying to laminate on the lipophilic photopolymer layer, there was a problem that the hydrophilic solution of the protective layer did not spread over the photopolymer layer surface due to the low surface tension of the photopolymer layer, resulting in uneven coating. .
[0008]
Further, in a bipolar sheet battery as disclosed in Patent Literature 2 and Patent Literature 3, it relates to the configuration of the electrodes and the connection of the electrode units. The thickness of the solid electrolyte is described in Experimental Example 1 of Patent Literature 2. Only an example using a 0.1 mm solid electrolyte sheet is disclosed, but no description is given of a method for polymerizing a polymer used for forming a solid electrolyte. However, the solid electrolyte has a lower ionic conductivity than the liquid electrolyte, and has a thickness of only 0.1 mm in a lithium ion battery that requires a high energy density and a high output density as a large-capacity power supply for an electric vehicle or the like. It has been found that even with such a thin solid electrolyte sheet, there is a problem in that even if the internal resistance of the thin solid electrolyte sheet is to be taken out, a high output can be obstructed.
[0009]
Accordingly, an object of the present invention is to provide a lithium ion battery using a solid electrolyte for an electrolyte layer, which can make the electrolyte layer thinner than a conventional solid electrolyte sheet.
[0010]
Another object of the present invention is to provide a lithium ion battery in which the internal resistance of the electrolyte layer is reduced as compared with a conventional solid electrolyte sheet, and the solid electrolyte is used for the electrolyte layer from which high output can be obtained. It is.
[0011]
[Means for Solving the Problems]
The present invention provides, in a lithium ion battery, (1) the constituent material particle size of the positive electrode is 8 μm or less, (2) the surface roughness Ra of the positive electrode is 1.4 μm or less, and (3) the constituent material particle size of the negative electrode is An all-solid-state polymer battery having at least one of the above-mentioned requirements (1) to (4), in which the surface roughness Ra of the negative electrode is 1.4 μm or less. Can be achieved by
[0012]
【The invention's effect】
According to the present invention, in a lithium ion battery, the particle size of an active material or a conductive additive contained in a positive electrode or a negative electrode is regulated to a specific size or less (8 μm or less), or the surface roughness Ra of the positive or negative electrode To a specific value or less (Ra = 1.4 μm or less), the thickness of the solid electrolyte layer formed between the positive electrode and the negative electrode can be reduced by a conventional solid electrolyte sheet (thickness 0). .About.1 mm) and the like (for example, 20 μm or less). As a result, the internal resistance is reduced, so that a high-output all solid polymer battery can be obtained.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0014]
The present invention relates to an all solid polymer type lithium ion battery using a solid electrolyte for the electrolyte layer, wherein (1) the particle size of the constituent material of the positive electrode is 8 μm or less, and (2) the surface roughness Ra of the positive electrode is 1 0.4 μm or less, (3) the particle size of the constituent material of the negative electrode is 8 μm or less, and (4) the surface roughness Ra of the negative electrode is 1.4 μm or less. I do. It is preferable that at least one requirement on the positive electrode side and one requirement on the negative electrode side be provided. Further, the thickness of the solid electrolyte layer between the positive electrode and the negative electrode is desirably 20 μm or less. This is because, in the application range of the prior art, even if the electrode surface is sufficiently smooth, as the thickness of the electrolyte layer is reduced to reduce the internal resistance, the unevenness (surface roughness) due to the particle size on the electrode surface is reduced. However, the ratio to the thickness of the electrolyte layer is relatively increased. For this reason, when a pressing force acts on the battery due to vibration or impact, there has been a problem in that a minute short circuit easily occurs through the electrolyte layer in a portion where the distance between the electrodes is narrow (a convex portion on the electrode surface). Therefore, in the related art, the thickness of the electrolyte layer is usually required to be about 0.1 mm. However, in the present invention, by satisfying the above requirements, the thickness of the electrolyte layer can be reduced without causing a problem such as a short circuit between the electrodes. Can be further reduced in thickness, and the internal resistance of the electrolyte layer can be reduced. Therefore, the energy density and output density of the battery can be increased, high output can be taken out, and it can be effectively used as a large-capacity power supply for electric vehicles that are subject to vibration or shock during driving. And a lithium-ion battery using the same. Further, it is necessary to connect a large number of cells (cells) to a large-capacity power supply for an electric vehicle, and the thinning of the electrolyte layer can sufficiently contribute to downsizing of the power supply mounted on the vehicle. .
[0015]
Here, with the surface roughness Ra, only the reference length is extracted from the roughness curve in the direction of the average line, the x-axis is taken in the direction of the average line of the extracted portion, and the y-axis is taken in the direction of the vertical magnification. When the roughness curve is represented by y = f (x), the value obtained by the following equation 1 is represented by a micrometer (μm) (JIS B 0601-1994) (see FIG. 5). .
[0016]
(Equation 1)

[0017]
The method for measuring the surface roughness Ra can be measured by the method described in Examples described later, but is not particularly limited thereto. As described in the method described in Examples, the surface roughness Ra defined in the present invention can be measured relatively easily during the manufacturing process, and can be measured even after the battery is completed. Yes, since the results are almost the same, the Ra within the range of the present invention, if the measured Ra satisfies the requirements specified above, in either the manufacturing stage or after the completion of the battery, in only one of the stages. It can be said that it is included in. The surface roughness of the electrode is that of the surface on the side where the solid electrolyte layer is in contact with the electrode.
[0018]
The particle diameter of the constituent material of the positive electrode means the maximum particle diameter, and the particle diameter of the constituent material of the negative electrode also means the maximum particle diameter. Basically, the active material and the conductive additive correspond to these, but also include the maximum particle size of the filler used for improving the film strength. The method of measuring the particle size of the constituent materials of these two electrodes can be performed by the method described in Examples described later, but is not particularly limited thereto. As described in the method described in Examples, these particle sizes specified in the present invention can be easily measured from the raw materials used, and can be measured even after the battery is completed, and the results are almost the same. Therefore, whether the measured particle size satisfies the requirements specified above, in either the manufacturing stage (used raw material) or after the completion of the battery, in any one of the stages, the scope of the present invention is not limited. It can be said that it is included.
[0019]
The thickness of the solid electrolyte layer refers to the total thickness of the solid electrolyte film provided between the positive electrode and the negative electrode. The method for measuring the thickness of these solid electrolyte layers can be performed by the method described in Examples described later, but is not particularly limited thereto. As in the method described in the examples, the thickness of the solid electrolyte layer specified in the present invention can be easily measured from the thickness of the polymer electrolyte membrane or the solid electrolyte layer formed in the manufacturing process, It can be measured even after the battery is completed, and since the results are almost the same, the film thickness of the solid electrolyte layer measured at only one of the stages, either during the manufacturing stage or after the battery is completed, is as described above. Anything that satisfies the specified requirements can be said to be included in the scope of the present invention.
[0020]
The lithium ion battery that is the object of the present invention is not particularly limited as long as it is a lithium ion battery using a solid electrolyte for the electrolyte layer. For example, a bipolar type lithium ion battery, a non-bipolar type lithium ion battery, and the like can be given. However, this does not prevent application to other types of batteries as long as the effect such as high output characteristics can be obtained by reducing the internal resistance of the solid electrolyte layer. Further, they may be of a laminated type or a wound type, and are not limited to any form. Similarly, a primary battery or a secondary battery may be used. Preferably, it is a bipolar type lithium ion secondary battery. This is because a bipolar type lithium ion secondary battery can constitute a battery having excellent capacity and output characteristics. Furthermore, in a bipolar lithium ion secondary battery using a solid electrolyte as an electrolyte, there is no liquid junction problem, so that a bipolar battery having high reliability with a simple configuration and excellent output characteristics can be formed. It is.
[0021]
Hereinafter, a preferred embodiment of the lithium-ion battery of the present invention, which is a bipolar lithium-ion secondary battery using a solid electrolyte as an electrolyte (hereinafter, also simply referred to as a bipolar battery), will be described as an example. It goes without saying that the invention should not be limited to these.
[0022]
1 to 4 briefly explain the basic configuration of a bipolar battery with reference to the drawings. FIG. 1 shows a schematic cross-sectional view schematically illustrating the structure of a bipolar electrode constituting a bipolar battery. FIG. 2 is a schematic cross-sectional view schematically showing the structure of a unit cell layer constituting a bipolar battery. FIG. 3 is a schematic sectional view schematically showing the entire structure of the bipolar battery. FIG. 4 is a schematic diagram conceptually showing a symbolized representation in which a plurality of unit cell layers stacked in a bipolar battery are connected in series.
[0023]
As shown in FIGS. 1 to 4, a positive electrode (also referred to as a positive electrode layer) 2 is provided on one surface of a current collector 1 composed of one or more sheets, and a negative electrode (also referred to as a negative electrode layer) is provided on the other surface. The electrode layers 2 and 3 of the bipolar electrode 5 adjacent to the bipolar electrode 5 with the solid electrolyte layer 4 interposed therebetween face the bipolar electrode 5 provided with the solid electrolyte layer 4 (see FIG. 1). That is, in the bipolar battery 11, a plurality of bipolar electrodes (electrode layers) 5 having the positive electrode layer 2 on one surface of the current collector 1 and the negative electrode layer 3 on the other surface are provided via the electrolyte layer 4. It is composed of an electrode laminate (bipolar battery body) 7 having a laminated structure. The electrodes 5a and 5b of the uppermost layer and the lowermost layer do not have a bipolar electrode structure, but have a structure in which an electrode layer (positive electrode layer 2 or negative electrode layer 3) on only one side required for the current collector 1 (or terminal plate) is formed. I have.
[0024]
Also, the uppermost and lowermost electrodes 5a and 5b of the electrode stack 7 in which a plurality of such bipolar electrodes 5 and the like are stacked need not have a bipolar electrode structure, and are necessary for the current collector 1 (or terminal plate). A structure in which an electrode layer (the positive electrode layer 2 or the negative electrode layer 3) only on one side is provided (see FIG. 3). In the bipolar battery 11, the positive and negative electrode leads 8, 9 are respectively joined to the current collectors 1 at the upper and lower ends.
[0025]
The number of laminations of the bipolar electrode is adjusted according to a desired voltage. In the present invention, a sufficient output can be ensured even if the thickness of the sheet-shaped battery is made as thin as possible, so that the number of times of stacking the bipolar electrodes may be reduced.
[0026]
Further, in the bipolar battery 11 of the present invention, in order to prevent external impact and environmental degradation during use, the electrode laminate 7 is sealed in a battery exterior material (exterior package) 10 under reduced pressure, and the electrode leads 8, It is preferable to adopt a structure in which 9 is taken out of the battery exterior material (exterior package) 10 (see FIGS. 3 and 4). From the viewpoint of weight reduction, using a conventionally known battery exterior material such as a polymer-metal composite laminate film in which a metal (including an alloy) such as aluminum, stainless steel, nickel, and copper is coated with an insulator such as a polypropylene film. A configuration in which the electrode laminate 7 is housed, sealed under reduced pressure (sealed), and the electrode leads 8 and 9 are taken out of the battery exterior material 10 by joining a part or all of the peripheral portion by heat fusion. It is preferred that The basic configuration of the bipolar battery 11 can be said to be a configuration in which a plurality of stacked unit cell layers (single cells) 6 are connected in series, as shown in FIG.
[0027]
Hereinafter, components of the bipolar battery of the present invention will be mainly described.
[0028]
[Current collector]
The current collector that can be used in the present invention is not particularly limited, and a conventionally known current collector can be used. For example, an aluminum foil, a stainless steel (SUS) foil, a clad material of nickel and aluminum, a clad material of copper and aluminum, a clad material of SUS and aluminum, or a plating material of a combination of these metals can be preferably used. Alternatively, a current collector in which aluminum is coated on a metal surface may be used. In some cases, a current collector in which two or more metal foils are bonded may be used. In the case of using a composite current collector, as a material of the positive electrode current collector, for example, a conductive metal such as aluminum, an aluminum alloy, SUS, or titanium can be used, and aluminum is particularly preferable. On the other hand, as a material of the negative electrode current collector, for example, a conductive metal such as copper, nickel, silver, and SUS can be used, and SUS and nickel are particularly preferable. In the composite current collector, the positive electrode current collector and the negative electrode current collector may be electrically connected to each other directly or via a conductive intermediate layer made of a third material.
[0029]
The thickness of each of the positive electrode current collector and the negative electrode current collector in the composite current collector may be as usual, and is about 1 to 100 μm for both current collectors. Preferably, the thickness of the current collector (including the composite current collector) is about 1 to 100 μm from the viewpoint of reducing the thickness of the battery.
[0030]
[Positive electrode]
Here, as a constituent material of the positive electrode, any material containing a positive electrode active material may be used, and further, as necessary, a conductive auxiliary agent for increasing electron conductivity, a binder, a solid electrolyte, and a method for increasing ionic conductivity. And an electrolyte supporting salt.
[0031]
As the positive electrode active material, a composite oxide of a transition metal and lithium (lithium-transition metal composite oxide) can be suitably used. Specifically, LiMn ₂ O ₄ Li-Mn based composite oxides such as LiCoO ₂ Li-Co based composite oxides such as Li ₂ Cr ₂ O ₇ , Li ₂ CrO ₄ LiNiCr-based composite oxides such as LiNiO ₂ Li-Ni-based composite oxides such as LiFeO ₂ Li-Fe-based composite oxides such as those obtained by substituting some of these transition metals with other elements, and the like can be used. However, the present invention is limited to these materials. It is not done. These lithium-transition metal composite oxides are excellent in reactivity and cycle durability, and are low-cost materials. Therefore, using these materials for the electrode is advantageous in that a battery having excellent output characteristics can be formed. In addition, LiFePO ₄ Phosphoric acid compounds and sulfuric acid compounds of transition metals and lithium; ₂ O ₅ , MnO ₂ , TiS ₂ , MoS ₂ , MoO ₃ Transition metal oxides and sulfides such as PbO ₂ , AgO, NiOOH and the like.
[0032]
Examples of the conductive assistant include acetylene black, carbon black, and graphite. However, it is not limited to these.
[0033]
As the binder, polyvinylidene fluoride (PVDF), SBR, polyimide or the like can be used. However, it is not limited to these.
[0034]
In the present invention, since a solid electrolyte is used for the electrolyte layer, it is preferable that the positive electrode also contains the solid electrolyte. By filling the gap between the positive electrode active materials in the positive electrode with the solid electrolyte, the ionic conduction in the positive electrode becomes smooth, and the output of the entire bipolar lithium ion battery can be improved.
[0035]
The solid electrolyte is made of a polymer having ionic conductivity, and the material is not limited as long as it has ionic conductivity. Preferably, a polymer that can be produced by forming a crosslinkable structure of a polymerizable polymer for forming a solid electrolyte by thermal polymerization, ultraviolet polymerization, radiation polymerization, or electron beam polymerization is desirable because excellent mechanical strength is exhibited. Such a polymerizable polymer for forming a solid electrolyte needs to have at least an ether bond in the molecular structure and a polymerizable functional group at a terminal. The polymerizable functional group may be a general double bond. In addition, the main chain portion serving as the basic skeleton of this polymer is a 3 to 6 functional group, the side chain linked to each functional group is a random copolymer containing an ether bond, and each terminal has a double polymerizable functional group as a polymerizable functional group. It may be a copolymer having a bond. When a polymerization reaction is performed by adopting this structure, a network-like polymer can be obtained. Further, the random copolymer of each side chain can be obtained from polyethylene oxide or polypropylene oxide.
[0036]
Known polymerizable polymers such as polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof (see Examples) can be used as the polymerizable polymer. These polyalkylene oxide polymers such as PEO and PPO are excellent in that they can well dissolve the following electrolyte supporting salt. In the present invention, the solid electrolyte is contained in at least one of the positive electrode and the negative electrode. However, in order to further improve the battery characteristics of the bipolar battery, it is preferable that both are included.
[0037]
As an electrolyte supporting salt, for example, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiTaF ₆ , LiAlCl ₄ , Li ₂ B ₁₀ Cl ₁₀ Inorganic acid anion salts such as Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, LiC ₄ F ₉ SO ₃ , LiCF ₃ SO ₃ , Li (C ₂ F ₅ PF ₃ ), Or a mixture thereof. However, it is not limited to these.
[0038]
In the positive electrode, the amounts of the components such as the positive electrode active material, the conductive auxiliary agent, the binder, the solid electrolyte, and the electrolyte supporting salt are determined in consideration of the purpose of use of the battery (emphasis on output, energy, etc.) and ionic conductivity. Good. For example, in the case of a solid electrolyte, if the amount of the solid electrolyte in the positive electrode is too small, the ion conduction resistance and the ion diffusion resistance in the positive electrode increase, and the battery performance is reduced. On the other hand, if the blending amount of the solid electrolyte in the positive electrode is too large, the energy density of the battery decreases. Therefore, the solid electrolytic mass that meets the purpose is determined in consideration of these factors.
[0039]
The thickness of the positive electrode is not particularly limited and should be determined in consideration of the intended use of the battery (e.g., emphasis on output, energy, etc.) and ion conductivity, as described for the blending amount. The thickness of a general positive electrode is about 10 to 500 μm.
[0040]
In the present invention, it is desirable to use a material having a particle diameter of 8 μm or less, preferably 6 μm or less, for the constituent material of the positive electrode. This is because it is extremely useful for reducing the unevenness (surface roughness) of the electrode surface and further reducing the electrode resistance of the bipolar battery. In addition, the reason why the maximum particle size is defined instead of the generally used average particle size is that it is extremely important to exclude those having a large particle size contained in the constituent material of the positive electrode. . As a result, as described above, it is possible to prevent the formation of unevenness due to the constituent material of the positive electrode having a large particle diameter on the electrode surface, and to effectively prevent the problem of short circuit due to thinning of the electrolyte layer. is there. Note that the constituent material of the positive electrode here is mainly a positive electrode active material, but other examples include a conductive auxiliary. The binder, the solid electrolyte, and the electrolyte supporting salt fill gaps between these powders and form irregularities on the surface of the positive electrode, and do not cause an increase in surface roughness. It shall not be included in the definition of particle size.
[0041]
In the present invention, the surface roughness Ra of the positive electrode is 1.4 μm or less, preferably 1.1 μm or less. This can also effectively prevent the problem of micro short circuit due to the thinning of the electrolyte layer, and can contribute to the reduction of the internal resistance of the solid electrolyte. In addition, since a solid electrolyte is used for the electrolyte layer, even if the electrode surface is densified by pressing or the like as in the case of using a liquid electrolyte, there is also a problem that the internal permeability of the electrolyte is prevented and the charge / discharge characteristics are affected. Therefore, good charge / discharge characteristics can be exhibited. When the requirement for the surface roughness Ra is satisfied, it can be achieved, for example, by using a material having a particle diameter of 8 μm or less for the constituent material of the positive electrode. This is advantageous in that particles having a particle size of more than 8 μm can be used. In this case, for example, after forming a positive electrode on one side of the current collector (and further on the other side, a negative electrode), a pressing operation is performed, if necessary, in a cold or warm state to reduce the surface roughness Ra. It can be adjusted to 1.4 μm or less.
[0042]
[Negative electrode]
The negative electrode (negative electrode layer) contains a negative electrode active material. In addition, a conductive aid for improving electron conductivity, a binder, an electrolyte supporting salt for improving ionic conductivity, a solid electrolyte, and the like may be included.
[0043]
In the present invention, since the solid electrolyte is used for the electrolyte layer, it is desirable that the negative electrode also contains the solid electrolyte. By filling the voids between the negative electrode active materials in the negative electrode with the solid electrolyte, ionic conduction in the negative electrode becomes smooth, and the output of the entire bipolar lithium ion battery can be improved.
[0044]
Except for the type and shape of the negative electrode active material, the contents are basically the same as those described in the section of “Positive electrode”, and thus, here, the type and shape of the negative electrode active material and the negative electrode Descriptions other than the particle diameter of the constituent material and the surface roughness Ra of the negative electrode are omitted.
[0045]
As the negative electrode active material, a negative electrode active material that is also used in a solution-based lithium ion battery using a liquid electrolyte can be used. Specifically, carbon, a metal compound, a metal oxide, a Li metal compound, a Li metal oxide, or the like can be used. These may be used alone or in combination of two or more. Preferably, it is carbon or a lithium-transition metal composite oxide. These are excellent in reactivity and cycle durability, and are low cost materials. Therefore, by using these materials for the electrodes, a battery having excellent output characteristics can be formed. As the carbon, for example, graphite carbon, hard carbon, soft carbon, or the like can be used. In addition, as the lithium-transition metal composite oxide, for example, Li ₄ Ti ₅ O ₁₂ And the like can be used. As the metal compound, LiAl, LiZn, Li ₃ Bi, Li ₃ Cd, Li ₃ Sd, Li ₄ Si, Li _4.4 Pb, Li _4.4 Sn, Li _0.17 C (LiC ₆ ), The metal oxide is InO ₂ , SiO, SnO, SnO ₂ , SnSO ₄ , ZnO, CoO, NiO, FeO, etc., as a Li metal compound, Li ₃ FeN ₂ , Li _2.6 Co _0.4 N, Li _2.6 Cu _0.4 From N and the like, Li metal oxide (lithium-transition metal composite oxide) is Li ₄ Ti ₅ O ₁₂ Li _x Ti _y O _z Selected from lithium-titanium composite oxides and the like.
[0046]
The shape of the constituent material of the negative electrode varies depending on the type and the like, and examples thereof include a flat plate, a corrugated plate, a rod, and a powder, but are not limited thereto. Any material that satisfies the requirements of the particle size of the constituent material of the negative electrode or the surface roughness Ra of the negative electrode and can achieve the object of the present invention can be used without any problem, but the negative electrode is preferably used. An optimum shape that can improve battery characteristics such as charge / discharge characteristics may be appropriately selected depending on the type of the constituent material of the electrode.
[0047]
The microstructure of the constituent material of the negative electrode also has a different shape depending on the type and the like, and examples thereof include, but are not limited to, a lamination, a sphere, a fiber, a spiral, and a fibril. Also in this case, any material that satisfies the requirements of the particle size of the constituent material of the negative electrode or the surface roughness Ra of the negative electrode and can achieve the object of the present invention can be used. Although it can be used, preferably, a material having an optimal microstructure capable of improving battery characteristics such as charge / discharge characteristics may be appropriately selected according to the type of constituent material of the negative electrode.
[0048]
The thickness of the negative electrode is not particularly limited, and should be determined in consideration of the intended use of the battery (e.g., emphasis on output, energy, etc.) and ionic conductivity, as described for the blending amount. The thickness of a general negative electrode is about 10 to 500 μm.
[0049]
In the present invention, it is desirable to use a constituent material of the negative electrode having a particle diameter of 8 μm or less, preferably 6 μm or less. This is for the same reason as described in the section “Particle size of constituent material of positive electrode”, and the same effect is brought about, so that the description here is omitted. Also, the constituent materials of the negative electrode are the same as those described for “the constituent materials of the negative electrode”, and thus description thereof will be omitted.
[0050]
In the present invention, it is more preferable that the particle diameters of the constituent materials of the positive electrode and the negative electrode are both 8 μm or less, so that the solid electrolyte layer that can be formed between these electrodes can be further thinned.
[0051]
In the present invention, the surface roughness Ra of the negative electrode is 1.4 μm or less, preferably 1.1 μm or less. This is for the same reason as described in the section of “Surface Roughness Ra of Positive Electrode”. Since the same effect is obtained and adjustment can be performed in the same manner, the description is omitted here.
[0052]
[Solid electrolyte layer]
The solid electrolyte constituting the solid electrolyte layer (hereinafter, also simply referred to as an electrolyte layer) of the present invention is composed of a polymer having ionic conductivity, and the material is not limited as long as it exhibits ionic conductivity. Preferably, a polymer that can be produced by forming a crosslinkable structure of a polymerizable polymer for forming a solid electrolyte by thermal polymerization, ultraviolet polymerization, radiation polymerization, or electron beam polymerization is desirable because excellent mechanical strength is exhibited. Since there is no liquid leakage in the solid electrolyte constituting such a solid electrolyte layer, it is possible to form a lithium ion battery having high reliability without a liquid junction problem, and having excellent output characteristics with a simple configuration.
[0053]
The polymerizable polymer is basically the same as the content described in the section of “Positive electrode”, and the description is omitted here.
[0054]
The polymerizable polymer contains an electrolyte supporting salt to secure ion conductivity. The electrolyte supporting salt is basically the same as the content described in the section of “Positive electrode”, and the description thereof is omitted.
[0055]
The solid electrolyte can be included in the electrolyte layer, the positive electrode, and the negative electrode. However, the same solid electrolyte may be used, or different solid electrolytes may be used.
[0056]
By controlling the surface properties of the positive electrode and / or the negative electrode, the thickness of the electrolyte layer can be reduced to a level which has been difficult to achieve conventionally. The thinner the better, the better. Specifically, the thickness is 30 μm or less, preferably 20 μm or less, more preferably 5 to 20 μm, and particularly preferably 5 to 15 μm. Note that the lower limit of the thickness of the electrolyte layer is a value that can be made as thin as possible within a range where the function as the electrolyte layer can be ensured in obtaining a compact all solid polymer battery. Here, the thickness of the electrolyte layer refers to the thickness of the electrolyte layer provided between the positive electrode and the negative electrode. Therefore, depending on the method of forming the electrolyte layer, the electrolyte layer may be formed by bonding a plurality of polymer electrolyte membranes having the same or different thicknesses. And the thickness of the electrolyte layer formed by laminating the plurality of polymer electrolyte membranes.
[0057]
By the way, polymerizable polymers that are preferably used at present are polyether polymers such as PEO and PPO. For this reason, the oxidation resistance on the positive electrode side under high temperature conditions is weak. Therefore, when a positive electrode agent having a high oxidation-reduction potential is generally used in a solution-based lithium ion battery, the capacity of the negative electrode is preferably smaller than the capacity of the positive electrode opposed via the polymer solid electrolyte layer. preferable. When the capacity of the negative electrode is smaller than the capacity of the opposed positive electrode, it is possible to prevent the positive electrode potential from excessively rising at the end of charging. In addition, the capacity of the positive electrode and the negative electrode can be obtained from the manufacturing conditions as a theoretical capacity at the time of manufacturing the positive electrode and the negative electrode. The capacity of the finished product may be measured directly by a measuring device. However, if the capacity of the negative electrode is smaller than the capacity of the opposite positive electrode, the potential of the negative electrode may be too low and the durability of the battery may be impaired. For example, the average charge voltage of one cell layer (cell) is set to an appropriate value for the oxidation-reduction potential of the positive electrode active material to be used, and care is taken so that the durability does not decrease.
[0058]
[Insulating layer]
The insulating layer is formed around each electrode for the purpose of preventing adjacent current collectors from contacting each other in the battery and preventing a short circuit due to slight irregularities at the ends of the stacked electrodes. is there. In the present invention, an insulating layer may be provided around the electrodes as necessary. This means that when used as a vehicle drive or auxiliary power supply, even if a solid electrolyte is used to completely prevent a short circuit (liquid drop) due to the electrolytic solution, vibration or shock to the battery will last for a long time. Loaded. Therefore, from the viewpoint of prolonging the battery life, it is desirable to provide an insulating layer in order to ensure longer-term reliability and safety and to provide a high-quality large-capacity power supply. .
[0059]
As the insulating layer, any material having an insulating property, a sealing property against falling off of the solid electrolyte, a sealing property against moisture permeation from outside (sealing property), a heat resistance at a battery operating temperature, and the like may be used. , Epoxy resin, rubber, polyethylene, polypropylene, polyimide and the like can be used, but epoxy resin is preferred from the viewpoint of corrosion resistance, chemical resistance, ease of production (film forming property), economy, and the like.
[0060]
[Positive and negative terminal plates]
The positive and negative electrode terminal plates may be used as needed. That is, depending on the stacked (or wound) structure of the bipolar type lithium ion battery, the electrode terminal may be directly taken out from the outermost current collector, and in this case, the positive and negative electrode terminal plates may not be used.
[0061]
When using the positive and negative electrode terminal plates, in addition to having a function as a terminal, it is better to be as thin as possible from the viewpoint of thinning, but the laminated electrodes, electrolyte and current collector all have mechanical strength. Since they are weak, it is desirable to have sufficient strength to sandwich and support them from both sides. Further, from the viewpoint of suppressing the internal resistance at the terminal portion, it can be said that the thickness of the positive electrode and negative electrode terminal plates is usually preferably about 0.1 to 2 mm.
[0062]
As the material of the positive electrode terminal and the negative electrode terminal plate, a material usually used in a lithium ion battery can be used. For example, aluminum, copper, titanium, nickel, stainless steel (SUS), alloys thereof, and the like can be used. It is preferable to use aluminum from the viewpoints of corrosion resistance, ease of production, economy, and the like.
[0063]
The materials of the positive electrode terminal plate and the negative electrode terminal plate may be the same or different. Further, these positive and negative electrode terminal plates may be formed by laminating different materials from each other in multiple layers.
[0064]
The positive and negative electrode terminal plates only need to have the same size as the range up to the electrode forming portion of the current collector or the vicinity of the folding line set outside the electrode forming portion.
[0065]
[Positive and negative electrode leads]
As the positive and negative electrode leads, known leads used in a solution-based lithium ion battery using a liquid electrolyte can be used. In addition, the part taken out of the battery exterior material (battery case) does not affect the product (for example, automobile parts, especially electronic equipment, etc.) by contacting peripheral devices and wiring, etc. It is preferable to coat with a heat-shrinkable heat-shrinkable tube or the like.
[0066]
[Battery exterior material (battery case)]
For lithium ion batteries, not only bipolar batteries, but also external battery impacts and environmental degradation during use, the entire battery stack or battery winding, which is the battery body, is housed in a battery exterior material or battery case. It is desirable to do. From the viewpoint of weight reduction, a polymer-metal composite laminate film in which both surfaces of a metal (including an alloy) such as aluminum, stainless steel, nickel, and copper are coated with an insulator (preferably a heat-resistant insulator) such as a polypropylene film ( For example, by using a conventionally known battery exterior material such as a polypropylene-aluminum composite laminate film; also simply referred to as an aluminum laminate film), a part or all of its peripheral portion is joined by heat fusion to form a battery laminate. Is preferably housed and sealed. In this case, the positive electrode and the negative electrode lead may have a structure sandwiched between the heat-sealed portions and exposed to the outside of the battery exterior material. Use of a polymer-metal composite laminate film or the like having excellent thermal conductivity is preferable in that heat can be efficiently transmitted from a heat source of an automobile and the inside of the battery can be quickly heated to a battery operating temperature.
[0067]
The lithium-ion battery of the present invention may be used as a high-capacity power supply for an electric vehicle (EV), a hybrid electric vehicle (HEV), a fuel cell vehicle, a hybrid fuel cell vehicle, or the like, for example, as a high energy density and a high power density It can be suitably used for a vehicle drive power supply and an auxiliary power supply that require the above. In this case, it is preferable that the battery pack is formed by connecting a plurality of the lithium ion batteries of the present invention. That is, a high-capacity, high-output battery module can be formed by using at least two or more lithium-ion batteries of the present invention connected in series and / or in parallel to form a battery pack. . Therefore, it is possible to respond to the demand for the battery capacity and output for each purpose of use relatively inexpensively.
[0068]
Next, the method for producing a lithium ion battery according to the present invention satisfies at least one of the above-mentioned requirements (1) to (4) and further satisfies the requirement that the thickness of the solid electrolyte layer is 20 μm or less. There is no particular limitation as long as the obtained battery can be provided, and various conventionally known methods can be appropriately used.
[0069]
For example, in order to provide a battery satisfying the requirements of the above (1) and / or (3), for example, the particle size of the positive electrode and / or the negative electrode active material and the conductive additive used for the slurry material for the positive electrode and / or the negative electrode May be set to 8 μm or less.
[0070]
In order to provide a battery that satisfies the requirements of the above (2) and / or (4), for example, the positive electrode and / or the negative electrode may be cold or hot press-rolled, A slurry material for a positive electrode or a negative electrode satisfying the requirement of (3) may be used.
[0071]
Further, in order to provide a battery capable of satisfying the requirement that the thickness of the solid electrolyte layer is 20 μm or less, a polymer electrolyte membrane is formed on the surface of the positive electrode and / or the surface of the negative electrode, and then these are formed on the surface of the positive electrode and / or The surface of the negative electrode may be bonded via the polymer electrolyte membrane, and the thickness of the solid electrolyte layer formed by bonding the polymer electrolyte membranes at this time may be adjusted to 20 μm or less. The solid electrolyte layer having a thickness of 20 μm or less is formed, for example, by applying a solution containing a polymerizable polymer for forming a polymer electrolyte film on a positive electrode and / or a negative electrode, and then attaching a transparent substrate to the transparent electrolyte. It can be manufactured by irradiating ultraviolet rays from the substrate side and then removing the transparent substrate. Alternatively, it is also produced by applying a solution containing a polymerizable polymer for forming a polymer electrolyte membrane on a positive electrode and / or a negative electrode, and then bonding the positive electrode and the negative electrode and performing polymerization by a heating operation. be able to.
[0072]
Hereinafter, a method for manufacturing a bipolar lithium-ion battery using a solid electrolyte for an electrolyte layer, which is one of preferred aspects of the method for manufacturing a lithium-ion battery of the present invention, will be described as an example. They should not be restricted at all.
[0073]
(1) Application of positive electrode composition
First, an appropriate current collector (including a positive electrode current collector) is prepared. The positive electrode composition is usually obtained as a slurry (a positive electrode slurry), and is applied to one surface of a current collector (or a positive electrode current collector).
[0074]
The positive electrode slurry is a solution containing a positive electrode active material. As other components, a conductive auxiliary, a binder, a polymerization initiator, a polymerizable polymer which is a raw material of the solid electrolyte, an electrolyte supporting salt, and the like are optionally included. For example, the positive electrode slurry can be obtained by adding a polymerizable polymer and a conductive additive to a solvent containing a positive electrode active material, further adding a polymerization initiator and an electrolyte support salt, and stirring the mixture with a homomixer or the like.
[0075]
Regarding the polymer raw material (polymerizable polymer) of the positive electrode active material, the conductive auxiliary agent, the binder, the electrolyte supporting salt, and the solid electrolyte, the term “positive electrode” which is basically a constituent element of the “lithium ion battery of the present invention” Since the contents are the same as those described in, the description is omitted here.
[0076]
In the present invention, it is desirable to use a raw material (limited to powder) of the slurry for the positive electrode having a particle size of 8 μm or less so that the particle size of the constituent material of the positive electrode is 8 μm or less. As a result, the surface roughness Ra of the positive electrode can be reduced to 1.4 μm or less without performing a pressing operation after the preparation of the positive electrode, so that the operation and effect of the present invention can be achieved and the number of steps can be reduced. it can.
[0077]
The polymerization initiator needs to be appropriately selected according to the polymerization method (thermal polymerization method, ultraviolet polymerization method, radiation polymerization method, electron beam polymerization method, etc.) and the compound to be polymerized. For example, benzyl dimethyl ketal as an ultraviolet polymerization initiator and azobisisobutyronitrile as a thermal polymerization initiator are exemplified, but not limited thereto.
[0078]
The slurry viscosity adjusting solvent such as N-methyl-2-pyrrolidone (NMP) and n-pyrrolidone is appropriately selected according to the type of the slurry for the positive electrode.
[0079]
The amounts of the positive electrode active material, the electrolyte supporting salt, and the conductive additive may be adjusted according to the purpose of use of the bipolar battery, and the amounts usually used may be added. The amount of the polymerization initiator to be added is determined according to the number of crosslinkable functional groups contained in the polymer material (polymerizable polymer) for the solid electrolyte. Usually, it is about 0.01 to 1% by mass based on the above polymer raw material.
[0080]
(2) Formation of positive electrode
The current collector (including the positive electrode current collector) coated with the positive electrode slurry is dried to remove the contained solvent. At the same time, the polymerizable polymer is polymerized (cross-linked) by heat, ultraviolet rays, radiation, an electron beam or the like with the slurry for the positive electrode, thereby forming a positive electrode on the current collector. For drying or thermal polymerization, a conventionally known apparatus such as a vacuum dryer can be used. The conditions of the drying or thermal polymerization are determined according to the slurry for the applied positive electrode, and cannot be uniquely defined. For example, the conditions of the drying or thermal polymerization are usually from 40 to 150 ° C. for 5 minutes to 20 hours.
[0081]
In the present invention, it is desirable to adjust the surface roughness Ra of the positive electrode to be 1.4 μm or less. As a specific adjustment method, it is possible to use a raw material (limited to powder) having a particle size of 8 μm or less as a raw material of the slurry for the positive electrode, without any pressing operation after the preparation of the positive electrode. When the raw material (limited to powder) having a particle size of more than 8 μm is used for the positive electrode slurry, it can be adjusted by performing a pressing operation after the preparation of the positive electrode. The pressing operation may be either a cold press roll method or a hot press roll method, but in the case of a hot press roll method, the temperature is equal to or lower than the temperature at which the electrolyte supporting salt or the polymerizable polymer is decomposed (for example, , Example 3). The pressing pressure is desirably 200 to 1000 kg / cm in linear pressure. If the pressing pressure is less than 200 kg / cm in linear pressure, it may be difficult to reduce the surface roughness Ra to 1.4 μm or less, depending on the particle size of the constituent material of the positive electrode. On the other hand, when the pressing pressure exceeds 1000 kg / cm in linear pressure, distortion occurs due to the difference in hardness between the current collector metal and the coated electrode surface, causing twists and the like, and the active material particles in the positive electrode. Etc. may be crushed or the active material particles may be pressed against each other to affect the charge / discharge characteristics. It should be noted that, even when the raw material (limited to powder) of the slurry for the positive electrode has a particle size of 8 μm or less, the pressing operation may be performed after the preparation of the positive electrode. Thereby, the surface roughness of the positive electrode can be further reduced, and the electrolyte layer that can be formed between the electrodes can be further reduced.
[0082]
(3) Application of composition for negative electrode
A negative electrode composition (negative electrode slurry) containing a negative electrode active material is applied to a surface of the current collector opposite to the surface on which the positive electrode is formed, or to one surface of the negative electrode current collector.
[0083]
The negative electrode slurry is a solution containing a negative electrode active material. As other components, a conductive auxiliary, a binder, a polymerization initiator, a polymer raw material of a solid electrolyte, an electrolyte supporting salt, and the like are optionally included. The raw materials used and the amounts added are the same as those described in the section of “(1) Application of positive electrode composition”, and thus description thereof is omitted here.
[0084]
Further, in the present invention, it is desirable to use each raw material (limited to powder) of the negative electrode slurry having a particle diameter of 8 μm or less so that the particle diameter of the constituent material of the negative electrode is 8 μm or less. This is also the same reason as described in the section of “(1) Application of positive electrode composition”, and the same effect is brought about, so that the description is omitted here.
[0085]
(4) Formation of negative electrode
The current collector (including the negative electrode current collector) to which the negative electrode slurry has been applied is dried to remove the contained solvent. At the same time, the polymerizable polymer is polymerized (cross-linked) by heat, ultraviolet rays, radiation, an electron beam or the like using the slurry for the negative electrode to form a negative electrode on the current collector. In the case of a current collector (excluding the negative electrode current collector), a bipolar electrode is completed (see FIG. 1). The drying and polymerization apparatus and conditions are the same as those described in the section of “(2) Formation of Positive and Negative Electrodes”, and thus description thereof will be omitted.
[0086]
In the present invention, it is desirable to adjust the surface roughness Ra of the negative electrode to be 1.4 μm or less. Regarding the specific method of adjusting the surface roughness Ra of the negative electrode, the pressing operation and pressing conditions used in the adjusting method, the point that the pressing operation can be applied even when using a slurry material having a particle size of 8 μm or less, etc. (2) Formation of Positive Electrode "is the same as that described in the section, and the description is omitted here.
[0087]
Further, the pressing operation described in the above section “(2) Formation of positive electrode” may be performed, for example, by forming a positive electrode on one surface of a current collector and forming a negative electrode on the other surface, and then pressing the positive electrode and the negative electrode. May be performed collectively. The pressing operation may be performed after forming the positive electrode on one surface of the positive electrode current collector, or the pressing operation may be performed after forming the negative electrode on one surface of the negative electrode current collector. Furthermore, after the positive electrode formed on the positive electrode current collector and the negative electrode are bonded on the negative electrode current collector, the pressing operation may be performed collectively. May be selected appropriately. Regarding the pressing conditions, whether the positive electrode or the negative electrode is used, or the case where the positive electrode and the negative electrode are collectively performed, the pressing conditions should be adjusted within the range described in the above section “(2) Formation of positive electrode”. Can be.
[0088]
The order of the steps (1) applying the composition for the positive electrode to (4) forming the negative electrode is not particularly limited. For example, the steps (3) and (4) may be performed first, and then the steps (1) and (2) may be performed. Further, the steps (1) and (3) may be simultaneously performed on both sides of the current collector, and the steps (2) and (4) may be simultaneously performed. Furthermore, the steps (1) and (3) may be performed separately (either may be performed first), and then the steps (2) and (4) may be performed simultaneously. The order of the steps 4) should not be limited at all.
[0089]
(5) Preparation of solid electrolyte layer (or polymer electrolyte membrane)
The solid electrolyte layer (or polymer electrolyte membrane) is, for example, a solution prepared by dissolving a raw material polymer (polymerizable polymer) of the solid electrolyte, an electrolyte supporting salt, and the like in a solvent such as NMP (“polymer electrolyte membrane forming polymer electrolyte membrane”). It is manufactured by polymerizing (curing) a solution containing a polymerizable polymer or simply referred to as a solution containing a polymerizable polymer) and drying by heating.
[0090]
For example, a polymerization polymer is added to a solvent on a positive electrode and / or a negative electrode whose surface roughness Ra is 1.4 μm or less by terminating the polymerization reaction in the above steps (1) to (4), A solution containing a polymerizable polymer prepared by adding and mixing an agent and an electrolyte-supporting salt is applied, and a support having a smooth surface in contact with the solution containing the polymerizable polymer is adhered tightly so that air bubbles do not remain. Below, thermal polymerization, ultraviolet polymerization, radiation polymerization, or electron beam polymerization is performed while maintaining a specific film thickness to produce a solid electrolyte layer or a polymer electrolyte membrane having a predetermined thickness. After the completion of the polymerization reaction, the support on the positive electrode and / or the negative electrode is removed, and a positive electrode and / or a negative electrode having a polymer electrolyte membrane on the surface is produced. In order to reduce the thickness of the solid electrolyte layer between the electrodes to 20 μm or less when these are bonded after drying sufficiently, in the present step, the specific thickness can be maintained as described above using, for example, a spacer. It is desirable to polymerize in a state.
[0091]
In addition, the above-mentioned polymerizable polymer-containing solution is applied to one or both of the surfaces of the positive electrode and the negative electrode, and after sandwiching these with a support, thermal polymerization, radiation polymerization, or electron beam polymerization can be performed. The thickness of the solid electrolyte layer is desirably 20 μm or less, and can be controlled using a spacer or the like.
[0092]
Alternatively, an electrolyte layer or a polymer electrolyte membrane laminated between the electrodes may be separately prepared. In this case, for example, a solution containing a polymerizable polymer for forming the polymer electrolyte membrane is coated on the support or an appropriate release film, and no air bubbles remain in another support or the release film. The solid electrolyte layer or the polymer electrolyte membrane having a predetermined thickness can be prepared by performing thermal polymerization, ultraviolet polymerization, radiation polymerization or electron beam polymerization while keeping the film in a specific thickness. Also in this case, the thickness of the solid electrolyte layer is desirably 20 μm or less, and can be controlled using a spacer or the like.
[0093]
As the support, an optimal support may be appropriately selected depending on the polymerization method. For example, in the case of performing polymerization by irradiating ultraviolet rays, it is necessary to use a support having ultraviolet transmittance, for example, a transparent substrate. When a thermal polymerization reaction is performed by heating, a support having heat resistance at a heating temperature may be used, and a heat-resistant resin film or resin sheet may be used. In addition, when polymerization is performed by irradiating an electron beam or radiation, since the electron beam or the radiation has a high transparency, the object can be achieved even when irradiated from the electrode side. Any material can be used as long as it can hold (support) the film thickness.
[0094]
Since the release film may be heated to about 80 ° C. during the manufacturing process, the release film has sufficient heat resistance at the temperature, and a solution containing a polymerizable polymer for forming a polymer electrolyte membrane. Since there is no reactivity and it is necessary to peel off and remove in the manufacturing process, it is desirable to use a material having excellent release properties. For example, polyethylene terephthalate (PET), polypropylene film and the like can be used, but are not limited thereto. It should not be done. Further, a film obtained by applying an appropriate release agent, for example, a silicone-based release agent or the like to these films and drying them can be used.
[0095]
Regarding the polymerization apparatus, a conventionally known polymerization apparatus may be selected depending on the polymerization method. For example, a vacuum dryer (vacuum oven) or the like can be used for performing a thermal polymerization reaction. Regarding the polymerization conditions, optimal conditions may be appropriately selected for each polymerization method. For example, the conditions for the thermal polymerization reaction are determined according to the above solution, and cannot be uniquely defined, but are usually from 30 to 110 ° C. For 0.5 to 12 hours.
[0096]
In addition, polymerization methods other than the above thermal polymerization, for example, when performing an ultraviolet polymerization reaction using an ultraviolet polymerization initiator, the solution is poured into a gap that is transparent to ultraviolet light, and an ultraviolet irradiation apparatus that can perform drying and photopolymerization. It is preferable to irradiate ultraviolet rays to form a polymer by polymerizing the polymer material (polymerizable polymer) of the solid electrolyte in the solution by a photopolymerization reaction (crosslinking reaction). However, it is a matter of course that the present invention is not limited to this method. Depending on the type of the polymerization initiator, radiation polymerization, electron beam polymerization, thermal polymerization, and the like are properly used.
[0097]
The width of the obtained solid electrolyte layer is often slightly smaller than the size of the electrode forming portion of the current collector of the bipolar electrode, but is not particularly limited.
[0098]
The components of the solution and the amounts thereof should be determined appropriately according to the purpose of use.
[0099]
(6) Lamination of bipolar electrode and solid electrolyte layer (or polymer electrolyte membrane)
{Circle around (1)} In the case of a bipolar electrode having an electrolyte layer (or a polymer electrolyte membrane) formed on one or both sides, an electrode on which an electrolyte layer (or a polymer electrolyte membrane) has been formed after sufficiently heating and drying under high vacuum. Is cut out to a suitable size, and a plurality of layers obtained by directly bonding the cut out electrodes are laminated to form a bipolar battery body (electrode laminate).
[0100]
(2) When the bipolar electrode and the electrolyte layer (or the polymer electrolyte membrane) are separately prepared, the bipolar electrode and the electrolyte layer (or the polymer electrolyte membrane) are appropriately heated and dried under high vacuum. Cut out multiple pieces to size. A bipolar battery main body (electrode laminate) is manufactured by laminating a plurality of layers obtained by laminating a predetermined number of cut-out bipolar electrodes and electrolyte layers (or polymer electrolyte membranes).
[0101]
The number of layers of the electrode stack is determined in consideration of battery characteristics required for a bipolar battery. In the outermost layer on the positive electrode side, an electrode in which only the positive electrode layer is formed on the current collector is arranged. In the outermost layer on the negative electrode side, an electrode in which only the negative electrode layer is formed on the current collector is arranged.
[0102]
In the step of obtaining a bipolar battery by laminating a bipolar electrode and an electrolyte layer (or a polymer electrolyte membrane) or laminating an electrode on which an electrolyte layer (or a polymer electrolyte membrane) is formed, moisture or the like is mixed into the inside of the battery. From the viewpoint of preventing this, it is preferable to carry out the reaction under an inert atmosphere. For example, a bipolar battery is preferably manufactured in an argon atmosphere or a nitrogen atmosphere.
[0103]
(7) Formation of insulating layer
In the present invention, for example, the periphery of the electrode forming portion of the electrode laminate is immersed or injected or impregnated with an epoxy resin (precursor solution) or the like with a predetermined width. In any case, the current collector is previously masked using a releasable masking material or the like. After that, the epoxy resin is cured to form an insulating portion, and then the masking material may be peeled off.
[0104]
(8) Lead terminal connection
A positive electrode terminal plate and a negative electrode terminal plate are respectively installed on both outermost electron conductive layers of the bipolar battery body (battery laminate), and a positive electrode lead and a negative electrode lead are further joined to the positive electrode terminal plate and the negative electrode terminal plate. (Electrically connected) (see FIG. 3). As a joining method of the positive electrode lead and the negative electrode lead, ultrasonic welding or the like having a low joining temperature can be preferably used, but it is not limited to this, and a conventionally known joining method may be appropriately used. Can be.
[0105]
(9) Packing (completion of battery)
Finally, the entire battery stack is sealed with a battery exterior material or a battery case in order to prevent external impact and environmental degradation, thereby completing a bipolar battery. At the time of sealing, a part of the positive electrode lead and the negative electrode lead is taken out of the battery. The material of the battery exterior material (battery case) is preferably a metal (aluminum, stainless steel, nickel, copper, or the like) whose inner surface is covered with an insulator such as a polypropylene film.
[0106]
An example described through the above steps (1) to (9) is shown below.
[0107]
First, a positive electrode slurry is applied to the aluminum side of the composite current collector made of aluminum and SUS and cured to prepare a positive electrode, and a negative electrode slurry is applied to the back SUS side and cured to form a negative electrode. Then, a solution containing a polymerizable polymer is applied to each electrode surface and cured to produce a plurality of integrated electrodes in which a polymer electrolyte membrane is produced. After these are sufficiently dried, a bipolar battery can be manufactured by stacking a plurality of layers. In this case, the electrode terminals (lead terminals) are taken out from the outermost current collector of the stacked bipolar battery body (electrode laminate), and the bipolar battery body can be sealed with, for example, an aluminum laminated film. Also, if necessary, a single electrode of a positive electrode and a negative electrode can be prepared and used as an outermost current collector of the above-described bipolar battery via a polymer electrolyte membrane (the uppermost layer and the lowermost layer in FIG. 3). Electrodes 5a, 5b).
[0108]
【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.
[0109]
In the following Examples and Comparative Examples, unless otherwise specified, a polyethylene oxide-polypropylene copolymer represented by the following formula was used as a polymerizable polymer for a positive electrode, a polymerizable polymer for a negative electrode, and a polymerizable polymer for an electrolyte membrane ( Copolymerization ratio m: n = 5: 1, weight average molecular weight of 8,000 to 9000) was used.
[0110]
Embedded image

[0111]
In addition, the surface roughness Ra of the positive electrode and the negative electrode was measured by the following methods.
[0112]
The surface roughness Ra was measured using a contact surface roughness meter (Surfcom 1400A, Tokyo Seiki Co., Ltd.). After the preparation of the positive electrode and the negative electrode, by cutting into about 20 mm square and measuring the surface roughness, the value of Ra can be obtained automatically by a personal computer attached to a contact type surface roughness meter. Further, a solid electrolyte membrane is laminated between the positive electrode and the negative electrode to produce an all solid polymer battery, and after performing battery performance evaluation (charge / discharge evaluation), each electrode is peeled off and the surface of the positive electrode surface or the negative electrode surface is removed. The surface roughness can be measured. When peeling is difficult, the cross section of the stacked batteries can be photographed with an optical microscope or SEM, and Ra can be determined from the surface shapes of the positive electrode and the negative electrode.
[0113]
The method for measuring the particle size of the constituent materials of the positive electrode and the negative electrode was performed by the following methods.
[0114]
As a method of measuring the particle size of the raw material to be used, it can be measured by a laser diffraction scattering method (Shimadzu SALD-2000A). In addition, as a method of measuring the particle diameter of the constituent material of each electrode after the battery is manufactured, it is possible to perform sampling in a cross-sectional direction with a microtome, and then measure by observation with a TEM.
[0115]
The thickness of the solid electrolyte layer was measured by the following methods.
[0116]
In the case where the solid electrolyte membrane is produced alone, it can be measured with a normal thickness gauge such as a dial gauge. As a method for measuring the solid electrolyte membrane after the production of the battery, the cut surface can be observed with an optical microscope to measure the thickness.
[0117]
Example 1
The production of the positive electrode is performed by using LiMn having an average particle size of 4 μm and a maximum particle size of 6 μm or less as a positive electrode active material. ₂ O ₄ 26 parts by mass, 8 parts by mass of acetylene black having an average particle size of 500 nm and a maximum particle size of 3 μm or less as a conductive additive, and 100 parts by mass of the above-described polyethylene oxide-polypropylene copolymer as a polymerizable polymer for a positive electrode. 0.1 parts by weight of thermal polymerization initiator AIBN (azobisisobutylnitrile) and electrolyte supporting salt Li (C ₂ F ₅ SO ₂ ) ₂ 66 parts by mass of a solution containing a polymerizable polymer in which 31 parts by mass of N was dissolved in an n-pyrrolidone solvent were weighed, and mixed and dispersed with a homomixer to prepare a positive electrode slurry. The positive electrode slurry was applied on an Al current collector (a positive electrode active material electrode current collector) with a coater, and thermally polymerized in an oven at 120 ° C. This was vacuum-dried at 90 ° C. to produce a 30 μm thick positive electrode. The surface roughness Ra of the obtained positive electrode was 1.1 μm.
[0118]
The production of the negative electrode is performed by using Li having an average particle size of 6 μm and a maximum particle size of 8 μm or less as a negative electrode active material. ₄ Ti ₅ O ₁₂ 26 parts by mass, 8 parts by mass of acetylene black having an average particle size of 500 nm and a particle size of 3 μm or less as a conductive aid, and 100 parts by mass of the aforementioned polyethylene oxide-polypropylene copolymer as a polymerizable polymer for a negative electrode. 0.1 parts by mass of thermal polymerization initiator AIBN (azobisisobutylnitrile) and electrolyte supporting salt Li (C ₂ F ₅ SO ₂ ) ₂ A negative electrode slurry was prepared by weighing 66 parts by mass of a solution containing a polymerizable polymer in which 31 parts by mass of N was dissolved in an n-pyrrolidone solvent, and mixing and dispersing them with a homomixer. The negative electrode slurry was applied on a SUS current collector (negative electrode current collector) by a coater, thermally polymerized in an oven at 120 ° C., and further dried in vacuum at 90 ° C. to produce a 35 μm thick negative electrode. The surface roughness Ra of the obtained negative electrode was 1.4 μm.
[0119]
The preparation of the polymer electrolyte membrane was carried out by adding 0.1 parts by mass of the ultraviolet polymerization initiator BDK (benzyl) to 20 parts by mass of the n-pyrrolidone solvent with respect to 100 parts by mass of the polyethylene oxide-polypropylene copolymer as the polymerizable polymer for the electrolyte membrane. Dimethyl ketal) and 48 parts by mass of electrolyte supporting salt Li (C ₂ F ₅ SO ₂ ) ₂ A solution in which N was dissolved was added and mixed to obtain a solution for forming an electrolyte membrane. The solution for forming an electrolyte membrane is applied onto the positive electrode so as to have a thickness (dry thickness) of about 8 μm, and a silicone-based release agent is previously applied and dried on the polypropylene film having a thickness of about 30 μm. The polymer was polymerized by irradiating ultraviolet rays for 20 minutes with the release agent coated side facing inward. After curing (after completion of the polymerization), the polypropylene film was removed, and then dried at 90 ° C. under vacuum to form a polymer electrolyte membrane on the positive electrode.
[0120]
Similarly, the above-mentioned solution for forming an electrolyte membrane is applied on the negative electrode so as to have a thickness (dry thickness) of about 7 μm, and a silicone-based release agent is previously applied thereon and dried to obtain a thickness of about 30 μm. The polypropylene films were superimposed on each other with the release agent coated side facing inward, and irradiated with ultraviolet rays for 20 minutes to polymerize the polymer. After the polymerization was completed (after curing), the polypropylene film was removed, and then dried at 90 ° C. under vacuum to form a polymer electrolyte membrane on the negative electrode.
[0121]
Each of the positive electrode and the negative electrode was cut into a size of 50 mm × 80 mm, and bonded to each other with the surfaces on which the polymer electrolyte membranes were formed to be inside, to produce an all solid polymer battery of Example 1.
[0122]
Further, even after the fabrication of the all solid polymer battery, the particle size of the constituent material of each electrode, the surface roughness Ra of each electrode, and the film thickness of the solid electrolyte layer (formed by bonding two polymer electrolyte membranes) are set as described above. As a result of the measurement, the particle diameter of the constituent material of the positive electrode was 6 μm or less, and the particle diameter of the constituent material of the negative electrode was 8 μm or less. The surface roughness Ra of the positive electrode was 1.1 μm, the surface roughness Ra of the negative electrode was 1.4 μm, and the thickness of the solid electrolyte layer was 15 μm.
[0123]
Example 2
The production of the positive electrode is performed by using LiMn having a particle size of 8 μm or less (8 μm mesh through (pass) size) as the positive electrode active material. ₂ O ₄ A positive electrode was produced in the same manner as in Example 1 except that the above was used. The production of the negative electrode is performed by using Li having a particle size of 8 μm or less (8 μm mesh through (pass) size) as the negative electrode active material. ₄ Ti ₅ O ₁₂ A negative electrode was produced in the same manner as in Example 1 except that the negative electrode was used.
[0124]
The positive electrode and the negative electrode were pressed at a linear pressure of 800 kg / cm using a roll press to prepare a positive electrode and a negative electrode having a surface roughness Ra of 1.3 μm.
[0125]
The preparation of the polymer electrolyte membrane was carried out by adding 0.1 parts by mass of the ultraviolet polymerization initiator BDK (benzyl) to 20 parts by mass of the n-pyrrolidone solvent with respect to 100 parts by mass of the polyethylene oxide-polypropylene copolymer as the polymerizable polymer for the electrolyte membrane. Dimethyl ketal) and 48 parts by mass of electrolyte supporting salt Li (C ₂ F ₅ SO ₂ ) ₂ A solution in which N was dissolved was added and mixed to obtain a solution for forming an electrolyte membrane. The solution for forming an electrolyte membrane is applied on the positive electrode so as to have a thickness (dry thickness) of about 10 μm, and a polypropylene film having a thickness of about 30 μm, which is previously coated with a silicone release agent and dried, is applied. The polymer was polymerized by irradiating ultraviolet rays for 20 minutes with the release agent coated side facing inward. After curing (after completion of the polymerization), the polypropylene film was removed, and then dried at 90 ° C. under vacuum to form a polymer electrolyte membrane on the positive electrode.
[0126]
Similarly, the solution for forming an electrolyte membrane is applied on the negative electrode so as to have a thickness (dry thickness) of about 5 μm, and a silicone-based release agent is applied thereon in advance and dried to a thickness of about 30 μm. The polypropylene films were superimposed on each other with the release agent coated side facing inward, and irradiated with ultraviolet rays for 20 minutes to polymerize the polymer. After curing (after completion of the polymerization), the polypropylene film was removed, and then dried at 90 ° C. under vacuum to form a polymer electrolyte membrane on the negative electrode.
[0127]
Each of the positive electrode and the negative electrode was cut into a size of 50 mm × 80 mm, and bonded to each other with the surfaces on which the polymer electrolyte membranes were formed to be inside, thereby producing an all solid polymer battery of Example 2.
[0128]
Further, even after the fabrication of the all solid polymer battery, the particle size of the constituent material of each electrode, the surface roughness Ra of each electrode, and the film thickness of the solid electrolyte layer (formed by bonding two polymer electrolyte membranes) are set as described above. As a result of the measurement, the particle size of the constituent material of the negative electrode was 8 μm or less, and the particle size of the constituent material of the negative electrode was 8 μm or less. The surface roughness Ra of the positive electrode was 1.3 μm, the surface roughness Ra of the negative electrode was 1.3 μm, and the thickness of the solid electrolyte layer was 15 μm.
[0129]
Example 3
The positive electrode and the negative electrode manufactured in Example 2 were pressed at a linear pressure of 400 kg / cm using a roll press heated to 140 ° C. to obtain a positive electrode and a negative electrode with a surface roughness Ra of 1.4 μm. .
[0130]
The preparation of the polymer electrolyte membrane was carried out by adding 0.1 parts by mass of the ultraviolet polymerization initiator BDK (benzyl) to 20 parts by mass of the n-pyrrolidone solvent with respect to 100 parts by mass of the polyethylene oxide-polypropylene copolymer as the polymerizable polymer for the electrolyte membrane. Dimethyl ketal) and 48 parts by mass of electrolyte supporting salt Li (C ₂ F ₅ SO ₂ ) ₂ A solution in which N was dissolved was added and mixed to obtain a solution for forming an electrolyte membrane. The solution for forming an electrolyte membrane is coated on the positive electrode so as to have a thickness (dry thickness) of about 10 μm, and a silicone-based release agent is previously coated and dried on the polypropylene film having a thickness of about 30 μm. They were superposed with the release agent coated side inside, and irradiated with ultraviolet rays for 20 minutes to polymerize the polymer. After curing (after the completion of the polymerization), the polypropylene film was removed, and the resultant was vacuum-dried at 90 ° C. to form a polymer electrolyte membrane on the positive electrode.
[0131]
Similarly, the solution for forming an electrolyte membrane is applied on the negative electrode so as to have a thickness (dry thickness) of about 5 μm, and a silicone-based release agent is applied thereon in advance and dried to a thickness of about 30 μm. The polypropylene films were superimposed on each other with the release agent coated side facing inward, and irradiated with ultraviolet rays for 20 minutes to polymerize the polymer. After curing (after completion of the polymerization), the polypropylene film was removed, and then dried at 90 ° C. under vacuum to form a polymer electrolyte membrane on the negative electrode.
[0132]
Each of the positive electrode and the negative electrode was cut into a size of 50 mm × 80 mm, and bonded to each other with the surface on which the polymer electrolyte membrane was formed being inside, to produce an all solid polymer battery of Example 3.
[0133]
Further, even after the fabrication of the all solid polymer battery, the particle size of the constituent material of each electrode, the surface roughness Ra of each electrode, and the film thickness of the solid electrolyte layer (formed by bonding two polymer electrolyte membranes) are set as described above. As a result of the measurement, the particle size of the constituent material of the negative electrode was 8 μm or less, and the particle size of the constituent material of the negative electrode was 8 μm or less. The surface roughness Ra of the positive electrode was 1.4 μm, the surface roughness Ra of the negative electrode was 1.4 μm, and the thickness of the solid electrolyte layer was 15 μm.
[0134]
Example 4
The positive electrode of Example 1 was formed on the aluminum side of a composite current collector (thickness: 60 μm) made of aluminum and SUS, and the negative electrode of Example 1 was formed on the SUS side on the back side. Then, the polymer electrolyte membrane of Example 1 was formed on the positive electrode and the negative electrode.
[0135]
Five integrated electrodes were produced and laminated. Further, the positive electrode and the negative electrode each having the polymer electrolyte membrane obtained in the same manner as in Example 1 as the outermost electrodes were bonded together with the surface on which the polymer electrolyte membrane was formed being inward, thereby forming a 6-cell configuration. A bipolar battery was prototyped (see FIG. 3).
[0136]
Note that measurement of the particle size of the constituent materials of each electrode, the surface roughness Ra of each electrode, and the thickness of the solid electrolyte layer (formed by bonding two polymer electrolyte membranes) after fabrication of the bipolar battery were carried out. The description is omitted because it is the same as in Example 1.
[0137]
Comparative Example 1
The production of the positive electrode is performed by using LiMn having an average particle size of 9 μm and a maximum particle size of 11 μm or less as a positive electrode active material. ₂ O ₄ 26 parts by mass, 8 parts by mass of acetylene black having an average particle size of 500 nm and a particle size of 3 μm or less as a conductive additive, and 100 parts by mass of the above-mentioned polyethylene oxide-polypropylene copolymer as a polymerizable polymer for a positive electrode. 0.1 parts by mass of a thermal polymerization initiator AIBN and an electrolyte supporting salt Li (C ₂ F ₅ SO ₂ ) ₂ 66 parts by mass of a solution containing a polymerizable polymer in which 31 parts by mass of N was dissolved in an n-pyrrolidone solvent were weighed and mixed and dispersed by a homomixer to prepare a positive electrode slurry. The positive electrode slurry was applied on an Al current collector (a positive electrode active material electrode current collector) with a coater, and thermally polymerized in an oven at 120 ° C. This was vacuum-dried at 90 ° C. to produce a 30 μm thick positive electrode. The surface roughness Ra of the obtained positive electrode was 1.8 μm.
[0138]
The production of the negative electrode is performed by using Li having an average particle size of 9 μm and a particle size of 11 μm or less as a negative electrode active material. ₄ Ti ₅ O ₁₂ 26 parts by mass, 8 parts by mass of acetylene black having an average particle size of 500 nm and a particle size of 3 nm or less as a conductive aid, and 100 parts by mass of the aforementioned polyethylene oxide-polypropylene copolymer as a polymerizable polymer for a negative electrode. 0.1 parts by mass of a thermal polymerization initiator AIBN and an electrolyte supporting salt Li (C ₂ F ₅ SO ₂ ) ₂ 66 parts by mass of a solution containing a polymerizable polymer in which 31 parts by mass of N was dissolved in an n-pyrrolidone solvent were measured and mixed and dispersed by a homomixer to prepare a negative electrode slurry. The negative electrode slurry was applied on a SUS current collector (negative electrode current collector) by a coater, thermally polymerized in an oven at 120 ° C., and further dried in vacuum at 90 ° C. to produce a 35 μm thick negative electrode. The surface roughness Ra of the obtained negative electrode was 1.8 μm.
[0139]
The preparation of the polymer electrolyte membrane was carried out by using 0.1 parts by mass of the ultraviolet polymerization initiator BDK and 48 parts by mass of 20 parts by mass of the n-pyrrolidone solvent with respect to 100 parts by mass of the polyethylene oxide-polypropylene copolymer as the polymerizable polymer for the electrolyte membrane. Parts by weight of electrolyte supporting salt Li (C ₂ F ₅ SO ₂ ) ₂ N was dissolved, and 0.1 part by mass of polyvinyl alcohol was further added and mixed to obtain a solution for forming an electrolyte membrane. The solution for forming an electrolyte membrane is applied on the positive electrode so as to have a thickness (dry thickness) of about 10 μm, and a polypropylene film having a thickness of about 30 μm, which is previously coated with a silicone release agent and dried, is applied. The polymer was polymerized by irradiating ultraviolet rays for 20 minutes with the release agent coated side facing inward. After curing (after completion of the polymerization), the polypropylene film was removed, and then dried at 90 ° C. under vacuum to form a polymer electrolyte membrane on the positive electrode.
[0140]
Similarly, the solution for forming an electrolyte membrane is applied on the negative electrode so as to have a thickness (dry thickness) of about 5 μm, and a silicone-based release agent is previously applied thereon and dried to obtain a thickness of about 30 μm. The polypropylene films were superimposed on each other with the release agent coated side facing inward, and irradiated with ultraviolet rays for 20 minutes to polymerize the polymer. After curing (after completion of the polymerization), the polypropylene film was removed, and then dried at 90 ° C. under vacuum to form a polymer electrolyte membrane on the negative electrode.
[0141]
Each of the positive electrode and the negative electrode was cut into a size of 50 mm × 80 mm, and attached to each other with the surfaces on which the polymer electrolyte membranes were formed, to produce an all solid polymer battery of Comparative Example 1.
[0142]
Further, even after the fabrication of the all solid polymer battery, the particle size of the constituent material of each electrode, the surface roughness Ra of each electrode, and the film thickness of the solid electrolyte layer (formed by bonding two polymer electrolyte membranes) are set as described above. As a result of a measurement method, the particle diameter of the constituent material of the negative electrode was 11 μm or less, and the particle diameter of the constituent material of the negative electrode was 11 μm or less. The surface roughness Ra of the positive electrode was 1.8 μm, the surface roughness Ra of the negative electrode was 1.8 μm, and the thickness of the solid electrolyte layer was 15 μm.
[0143]
Comparative Example 2
The production of the positive electrode is performed by using LiMn having an average particle size of 9 μm and a maximum particle size of 11 μm or less as a positive electrode active material. ₂ O ₄ 26 parts by mass, 8 parts by mass of acetylene black having an average particle size of 500 nm and a particle size of 3 μm or less as a conductive additive, and 100 parts by mass of the above-mentioned polyethylene oxide-polypropylene copolymer as a polymerizable polymer for a positive electrode. 0.1 parts by mass of a thermal polymerization initiator AIBN and an electrolyte supporting salt Li (C ₂ F ₅ SO ₂ ) ₂ 66 parts by mass of a solution containing a polymerizable polymer in which 31 parts by mass of N was dissolved in an n-pyrrolidone solvent were weighed and mixed and dispersed by a homomixer to prepare a positive electrode slurry. The positive electrode slurry was applied on an Al current collector (a positive electrode active material electrode current collector) with a coater, and thermally polymerized in an oven at 120 ° C. This was vacuum-dried at 90 ° C. to produce a 30 μm thick positive electrode. The surface roughness Ra of the obtained positive electrode was 1.8 μm.
[0144]
The production of the negative electrode is performed by using Li having an average particle size of 9 μm and a particle size of 11 μm or less as a negative electrode active material. ₄ Ti ₅ O ₁₂ 26 parts by mass, 8 parts by mass of acetylene black having an average particle size of 500 nm and a particle size of 3 nm or less as a conductive aid, and 100 parts by mass of the aforementioned polyethylene oxide-polypropylene copolymer as a polymerizable polymer for a negative electrode. 0.1 parts by mass of a thermal polymerization initiator AIBN and an electrolyte supporting salt Li (C ₂ F ₅ SO ₂ ) ₂ 66 parts by mass of a solution containing a polymerizable polymer in which 31 parts by mass of N was dissolved in an n-pyrrolidone solvent were measured and mixed and dispersed by a homomixer to prepare a negative electrode slurry. The negative electrode slurry was applied on a SUS current collector (negative electrode current collector) by a coater, thermally polymerized in an oven at 120 ° C., and further dried in vacuum at 90 ° C. to produce a 35 μm thick negative electrode. The surface roughness Ra of the obtained negative electrode was 1.8 μm.
[0145]
The preparation of the polymer electrolyte membrane was carried out by using 0.1 parts by mass of the ultraviolet polymerization initiator BDK and 48 parts by mass of 20 parts by mass of the n-pyrrolidone solvent with respect to 100 parts by mass of the polyethylene oxide-polypropylene copolymer as the polymerizable polymer for the electrolyte membrane. Parts by weight of electrolyte supporting salt Li (C ₂ F ₅ SO ₂ ) ₂ N was dissolved, and 0.1 part by mass of polyvinyl alcohol was further added and mixed to obtain a solution for forming an electrolyte membrane. The solution for forming an electrolyte membrane is applied onto the positive electrode so as to have a thickness (dry thickness) of about 50 μm, and a polypropylene film having a thickness of about 30 μm, which is previously coated with a silicone release agent and dried, is applied. The polymer was polymerized by irradiating ultraviolet rays for 20 minutes with the release agent coated side facing inward. After curing (after completion of the polymerization), the polypropylene film was removed, and then dried at 90 ° C. under vacuum to form a polymer electrolyte membrane on the positive electrode.
[0146]
Similarly, the above-mentioned solution for forming an electrolyte membrane is applied on the above-mentioned negative electrode so as to have a thickness (dry thickness) of about 50 μm, and a silicone-based release agent is applied thereon in advance and dried to obtain a thickness of about 30 μm. The polypropylene films were superimposed on each other with the release agent coated side facing inward, and irradiated with ultraviolet rays for 20 minutes to polymerize the polymer. After curing (after completion of the polymerization), the polypropylene film was removed, and then dried at 90 ° C. under vacuum to form a polymer electrolyte membrane on the negative electrode.
[0147]
Each of the positive electrode and the negative electrode was cut into a size of 50 mm × 80 mm, and attached to each other with the surfaces on which the polymer electrolyte membranes were formed to be inside, to produce an all solid polymer battery of Comparative Example 2.
[0148]
Further, even after the fabrication of the all solid polymer battery, the particle size of the constituent material of each electrode, the surface roughness Ra of each electrode, and the film thickness of the solid electrolyte layer (formed by bonding two polymer electrolyte membranes) are set as described above. As a result of a measurement method, the particle diameter of the constituent material of the negative electrode was 11 μm or less, and the particle diameter of the constituent material of the negative electrode was 11 μm or less. The surface roughness Ra of the positive electrode was 1.8 μm, the surface roughness Ra of the negative electrode was 1.8 μm, and the thickness of the solid electrolyte layer was 100 μm.
[0149]
<Evaluation results>
The performance evaluation of the all solid polymer batteries or the bipolar batteries of Examples 1 to 4 and Comparative Examples 1 and 2 was performed at a discharge rate of 5 C of electricity calculated from the amount of each active material. In addition, the presence or absence of a short circuit was determined based on the change in voltage in a standby state after charging (voltage drop of 10% or more / min).
[0150]
[Charging and discharging test method]
At 20 ° C., the battery was charged to 2.75 V with a constant current of 70 mA, waited for 10 minutes, and then discharged to 1.5 V with a constant current of 70 mA. The ratio of the discharge capacity to the charge capacity was determined and defined as the discharge rate.
[0151]
Table 1 shows the results.
[0152]
[Table 1]

[0153]
The evaluation criteria in the table are as follows.
[0154]
：: Voltage drop less than 1% / min
Δ: Voltage drop 1% or more / minute to voltage drop 10% or less / minute
×: Voltage drop of 10% or more / min
[Brief description of the drawings]
FIG. 1 is a schematic sectional view schematically showing a basic structure of a bipolar electrode constituting a bipolar battery of the present invention.
FIG. 2 is a schematic cross-sectional view schematically showing a basic structure of a unit cell layer (single cell) constituting the bipolar battery of the present invention.
FIG. 3 is a schematic sectional view schematically showing a basic structure of a bipolar battery of the present invention.
FIG. 4 is a schematic diagram schematically showing a basic configuration of a bipolar battery of the present invention.
FIG. 5 is a diagram illustrating the above-described formula 1 defined in JIS B 0601-1994 and the surface roughness Ra determined by the formula 1.
[Explanation of symbols]
1 ... current collector (metal foil) 2 ... positive electrode layer (positive electrode)
3 ... negative electrode layer (negative electrode), 4 ... solid electrolyte layer (electrolyte membrane),
5 ... Bipolar electrode,
5a: an electrode having a positive electrode layer disposed only on one required surface of the current collector;
5b: an electrode in which a negative electrode layer is arranged on only one required surface of the current collector,
6 ... unit cell layer (single cell) 7 ... electrode laminate,
8 ... Positive lead, 9 ... Negative lead,
10: battery exterior material; 11: bipolar battery.

Claims (11)

In a lithium ion battery, the all-solid-state polymer battery has a particle diameter of a constituent material of a positive electrode of 8 μm or less. 2. An all-solid polymer battery according to claim 1, wherein the surface roughness Ra of the positive electrode is 1.4 μm or less. An all-solid polymer battery according to claim 1, wherein the particle size of the constituent material of the negative electrode is 8 μm or less. 2. An all-solid polymer battery according to claim 1, wherein the surface roughness Ra of the negative electrode is 1.4 μm or less. An all solid polymer battery, characterized in that the lithium ion battery has at least two of the following requirements (1) to (4);
(1) The particle size of the constituent material of the positive electrode is 8 μm or less,
(2) the surface roughness Ra of the positive electrode is 1.4 μm or less;
(3) the constituent material of the negative electrode has a particle size of 8 μm or less;
(4) The surface roughness Ra of the negative electrode is 1.4 μm or less. The lithium ion battery according to any one of claims 1 to 5, wherein the thickness of the solid electrolyte layer between the positive electrode and the negative electrode is 20 µm or less. After preparing a polymer electrolyte membrane on the surface of the positive electrode and / or the surface of the negative electrode, these are laminated, and the total thickness of the solid electrolyte layers formed by laminating the polymer electrolyte membranes at this time is 20 μm or less. The method for producing an all solid polymer battery according to any one of claims 1 to 6, wherein: After applying a solution containing a polymerizable polymer for forming a polymer electrolyte membrane on the positive electrode and / or the negative electrode, a transparent substrate is attached, and after irradiating ultraviolet rays from the transparent substrate side, the transparent substrate is removed. The method for producing an all-solid-state polymer battery according to claim 7, wherein a polymer electrolyte membrane is produced. After applying a solution containing a polymerizable polymer for forming a polymer electrolyte membrane on the positive electrode and / or the negative electrode, the positive electrode and the negative electrode are attached to each other, and the polymer electrolyte membrane is polymerized by performing a heating operation. The method for manufacturing an all solid polymer battery according to claim 7, wherein the method is performed. One current collector made of one or two kinds of metals has a positive electrode on the surface, a negative electrode on the back, and a polymer electrolyte membrane formed on each electrode surface. The all solid polymer battery according to claim 1, wherein the all solid polymer battery is formed by laminating. The all-solid polymer battery according to any one of claims 7 to 9, wherein a positive electrode and / or a negative electrode is cold- or hot-pressed and then a solid electrolyte layer is formed. Production method.

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