JP2004273281A - Nonaqueous secondary battery - Google Patents
Nonaqueous secondary battery Download PDFInfo
- Publication number
- JP2004273281A JP2004273281A JP2003062701A JP2003062701A JP2004273281A JP 2004273281 A JP2004273281 A JP 2004273281A JP 2003062701 A JP2003062701 A JP 2003062701A JP 2003062701 A JP2003062701 A JP 2003062701A JP 2004273281 A JP2004273281 A JP 2004273281A
- Authority
- JP
- Japan
- Prior art keywords
- positive electrode
- secondary battery
- mass
- polymer
- coating film
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、非水二次電池に関し、さらに詳しくは、高容量で、かつサイクル特性が優れた非水二次電池に関する。
【０００２】
【従来の技術】
電子機器の小型化、携帯電話の普及に伴い、高エネルギー密度を有する二次電池への要求がますます高まっている。現在、この要求に応える高容量二次電池としては、正極活物質としてＬｉＣｏＯ２ 、ＬｉＮｉＯ２ 、ＬｉＭｎ２ Ｏ４ などのリチウム含有複合酸化物を用い、負極活物質として炭素系材料を用いたリチウムイオン二次電池が商品化されている。このリチウムイオン二次電池は、平均駆動電圧が３．６Ｖと高く、従来のニッケル−カドミウム電池やニッケル水素電池の約３倍の平均駆動電圧を有しており、また、負極活物質として炭素系材料を用いることや、充放電に関与する移動体がリチウムイオンであることから、軽量化も期待できる。
【０００３】
このリチウムイオン二次電池は、従来のリチウム金属を負極とする非水二次電池とは異なり、上記活物質を結合剤などとともに溶剤中に分散させてペースト状の塗料を調製し、そのペースト状塗料を正極集電体または負極集電体としての作用を兼ねる導電性基体の両面に塗布し、乾燥して、それぞれ上記活物質などを含有する塗膜を形成し、必要に応じて圧縮して塗膜密度を高めて、帯状の正極および負極を作製し、それらの帯状の正極と負極をセパレータを介して渦巻状に巻回して渦巻状の電極体を形成し、その渦巻状の電極体を電池缶に挿入して電池が構成されている。そして、正極には正極活物質と結合剤以外に塗膜中のインピーダンスを低減させるために、炭素系材料などからなる導電助剤が添加されている。
【０００４】
今後、携帯情報端末機器の需要拡大により、高容量で、かつ軽量のリチウムイオン二次電池の需要もますます増加し、それに伴って要求特性はさらに厳しくなることが予測される。リチウムイオン二次電池の高容量化は、負極材料の改良によるところが大きく、現在もＳｉ系やＳｎ系などの金属複合材料やＬｉ含有窒化物によるさらなる容量アップが検討されている。しかし、充放電による負極材料の膨潤や充放電サイクルによる容量劣化や安全性などにより、実用化には至らず、現在の負極材料の多くは炭素系材料で占められ、理論容量である３７２ｍＡｈ／ｇに近づきつつある。
【０００５】
一方、正極活物質に関しては、一般にＬｉＣｏＯ２ 、ＬｉＭｎＯ２ 、ＬｉＮｉＯ２ などのリチウム含有複合酸化物が用いられている。それぞれの正極活物質の理論放電容量は、ＬｉＣｏＯ２ が２７４ｍＡｈ／ｇ、ＬｉＭｎ２ Ｏ４ が１４８ｍＡｈ／ｇ、ＬｉＮｉＯ２ が２７４ｍＡｈ／ｇである。ＬｉＣｏＯ２ の実用的な放電容量は、１２５〜１４０ｍＡｈ／ｇ程度であるのに対して、ＬｉＮｉＯ２ の実用的な放電容量は１６０〜２００ｍＡｈ／ｇ程度である。そのため、ＬｉＮｉＯ２ は、ＬｉＣｏＯ２ に比べて高容量化が可能であるが、ＬｉＣｏＯ２ に比べて製造コストが高く、安全性の低いことが大きな課題になっている。また、ＬｉＭｎＯ２ の理論放電容量は１４８ｍＡｈ／ｇであり、さらに真密度が４．０〜４．２ｇ／ｃｃとＬｉＣｏＯ２ の真密度４．９〜５．１ｇ／ｃｃに比べて低い値を示す。従って、ＬｉＭｎＯ２ を使用した場合、単位体積当たりの容量がＬｉＣｏＯ２ よりも劣るのが明白である。これらのことから、現在、正極活物質としてＬｉＣｏＯ２ を用いることが一般的となっており、高容量化は塗膜構造の最適化によってなされている。
【０００６】
正極塗膜は、正極活物質、結合剤および導電助剤を主剤として構成される。この正極塗膜の作製方法は、溶剤中に正極活物質、結合剤および導電助剤などを均一に分散させ、ペースト状の正極塗料を調製し、金属箔などからなる導電性基体上に正極塗料を均一に塗布し、乾燥工程、圧縮工程を経て正極集電体としての作用を兼ねる導電性基体上に正極塗膜が作製される。正極の高容量化は、前記のように、正極活物質で高容量化が図れない以上、電池内部に如何に多く正極活物質を含有させるかということにかかっている。
【０００７】
単位体積当たりの正極活物質密度は、塗膜密度および塗膜中の正極活物質含有率に依存する。塗膜密度は、圧縮工程の圧力上昇により高密度化が図れるが、そうした場合、高圧力による正極の集電体切れや塗膜内部への電解液（液状電解質）の浸透性が低下することが懸念され、それによって、生産性の低下や電池特性の劣化が考えられる。一方、正極塗膜中の活物質含有率の増加は、結合剤や導電助剤の減少を伴う。結合剤の減少は、正極の塗膜強度や塗膜と導電性基体との接着性の低下が懸念されるため、極めて難しい。また、導電助剤は正極塗膜の導電性を保ち、電池内部インピーダンスに影響を与えるため、如何に導電性を維持して導電助剤量を低減するかが課題となる。
【０００８】
そこで、導電助剤の含有量を低減しても高い導電性が確保できるようにするために、これまでにも、導電助剤の改良策として高比表面積のグラファイト粒子を用いること（特許文献１参照）や大粒径グラファイト粉末と小粒径アセチレンブラック粉末とを併用する方法（特許文献２参照）が提案されている。
【０００９】
【特許文献１】
特開平１０−１４４３２０号公報（第１頁）
【００１０】
【特許文献２】
特開２０００−２７７０９５号公報（第２頁）
【００１１】
しかしながら、特許文献１のように、高比表面積のグラファイト粒子を導電助剤として用いた場合、高比表面積のグラファイトはいわゆる吸油量が大きいため、塗料化において多量の溶剤が必要になって、分散効率が思うように向上しない。また、特許文献２のように、大粒径グラファイト粉末と小粒径アセチレンブラック粉末とを併用した場合も、小粒径のアセチレンブラック粉末が高比表面積を有するため、前記特許文献１の場合と同様の問題を有していた。また、未分散の炭素粉末が含まれることは塗膜密度の低減をも引き起こす。
【００１２】
そのため、カーボン粉末を液体中で高分散させる分散剤が種々提案されている。例えば、スチレン系共重合体とアクリル酸エステル系共重合体のブロック共重合体（特許文献３参照）、オレフィンまたは芳香族アルケニル化合物とエチレン性不飽和カルボン酸またはその無水物との共重合体の水溶性塩（特許文献４参照）、ポリオキシアルキレン鎖を有する（メタ）アクリル酸系またはマレイン酸系共重合体（特許文献５参照）などが提案されている。
【００１３】
【特許文献３】
特開平６−１４８９２７号公報（第２頁）
【００１４】
【特許文献４】
特開平８−２３９３６１号公報（第２頁）
【００１５】
【特許文献５】
特開平１１−２８６６４４号公報（第２頁）
【００１６】
しかしながら、それらの分散剤によっても、微小粒径のカーボン粒子をリチウムイオン二次電池などの非水二次電池の正極塗料に分散させる場合には、いずれも充分な分散性を有していなかった。
【００１７】
【発明が解決しようとする課題】
本発明は、上記のような従来の非水二次電池における問題点を解決し、高容量で、かつサイクル特性が優れた非水二次電池を提供することを目的とする。
【００１８】
【課題を解決するための手段】
本発明は、正極の導電助剤として水スラリーのｐＨ値が７．０より大きい塩基性炭素微粒子を用い、かつ主たる結合剤の他に下記の化学式（１）または化学式（２）で示される側鎖を有し、かつアニオン性官能基を有する高分子を用いることにより、塗料を高密度化させ、正極活物質含有率が高い正極塗膜を形成することが可能であることを見出し、前記課題を解決したものである。
【化２】
【００１９】
【発明の実施の形態】
次に、本発明が上記構成の採用によって、高容量で、かつサイクル特性が優れた非水二次電池を提供できる理由を説明するとともに、その構成について詳細に説明する。
【００２０】
導電助剤として用いる炭素微粒子の正極塗料中での分散性を向上させるためには、分散剤の選択が重要である。炭素微粒子表面の官能基量は酸化物微粒子などと比べると非常に少なく、通常の低分子タイプの界面活性剤では充分な吸着層をつくることができない。しかし、分散剤として１分子中に多数の吸着アンカーを持つ高分子分散剤を用いれば、官能基密度の低い低活性表面を持つ炭素微粒子の表面にも充分な吸着層を形成できる。特に分散性の劣る比表面積が１００ｍ２ ／ｇ以上の微小粒径の炭素微粒子の多くは塩基性表面を有しているので、吸着アンカーとしてはアニオン性の官能基が有効である。
【００２１】
また、正極活物質として広く用いられるコバルト酸リチウム（ＬｉＣｏＯ２ など）は塩基性の表面を持っている。従って、導電助剤の炭素微粒子が塩基性表面を有する場合は活物質と導電助剤とが静電反発により斥け合うため、高密度充填が困難である。しかし、炭素微粒子の表面に化学式（１）または化学式（２）で示される側鎖を有し、アニオン性官能基を有する高分子（以下、簡略化して「アニオン性高分子」という）の吸着層を形成すると、このアニオン性高分子が活物質表面にも吸着し導電助剤の炭素微粒子と活物質粒子とを物理的に接近させて塗膜の高密度化が実現できる。
【００２２】
本発明において、上記アニオン性高分子としては、すなわち、化学式（１）または化学式（２）で示される側鎖を有し、かつアニオン性官能基を有する高分子としては、例えば、アクリル酸、マレイン酸などを共重合することによって得られる高分子が適している。これらのカルボン酸部分は部分的にまたはその全てが金属塩、アンモニウム塩などの形で中和されていてもよく、このように塩になっている場合は、フリーの酸に比べて溶剤中での解離度が高いので炭素微粒子に対する吸着力が強く、より一層分散性が優れている。
【００２３】
このアニオン性高分子を添加することによる電池特性への効果は、より少ない導電助剤量で正極塗膜を作製する場合において顕著に発現する。すなわち、高密度でかつ活物質比率が高い正極塗膜を作製する場合において効果的である。具体的には、正極塗膜の密度が３．２５ｇ／ｃｍ３ 以上である場合、正極塗膜中における正極活物質の比率が、正極塗膜１００質量部に対して、９４質量部以上である場合に効果的である。
【００２４】
本発明において用いるアニオン性高分子は、その質量平均分子量（以下、これを簡略化して、「分子量Ｍｗ」で示す場合がある）は２．０×１０３ 〜１．５×１０６ であるものが好ましい。アニオン性高分子の分子量Ｍｗが２．０×１０３ より小さい場合は、導電助剤に対する吸着量が少ないため導電助剤の分散が不充分になり、また、アニオン性高分子の分子量Ｍｗが１．５×１０６ より大きい場合は、厚い吸着層のために導電性が妨げられたり凝集作用が生じて導電性が低下するおそれがある。
【００２５】
本発明において、上記アニオン性高分子は、正極塗膜１００質量部に対して、０．００５質量部〜１質量部添加して正極塗膜中に含有させるようにすることが好ましい。アニオン性高分子の含有率が正極塗膜１００質量部に対して０．００５質量部より少ない場合は、アニオン性高分子を添加した効果が充分に発現せず、また、１質量部より多い場合は、正極塗膜中に絶縁性のポリマーが増加するため、電池のインピーダンスの上昇を招き、電池特性を劣化させるおそれがある。
【００２６】
本発明において、アニオン性高分子を正極塗料中に含有させる方法に関しては特に制限はない。正極塗料は正極活物質を結合剤や導電助剤、有機溶媒とともに混合、分散して調製する。前記アニオン性高分子は、正極活物質、導電助剤、主たる結合剤を混合する際に添加してもよい。また、導電助剤と有機溶媒の分散液をあらかじめ調製する際にアニオン性高分子を添加し、その後、主たる結合剤、正極活物質を加え、正極塗料を調製する工程を経る方法を採用してもよく、この方法が最も効果的である。さらに、導電助剤とアニオン性高分子を無溶剤の状態で混合・分散し、その後に主たる結合剤、溶剤、正極活物質などを加えて正極塗料を調製してもよい。導電助剤として複数の材料を用いる場合は、必須成分として用いる塩基性炭素微粒子とアニオン性高分子と有機溶媒であらかじめ分散液を調製し、その後、他の導電助剤、主たる結合剤、正極活物質などを加え、正極塗料を調製する工程を経由する方法を採用することもできる。有機溶媒としては、例えば、Ｎ−メチル−２−ピロリドン、ジメチルアセトアミド、ジメチルホルムアミドなど非プロトン性有機溶媒を単独または２種以上混合したものを用いることができる。
【００２７】
これらの混合・分散に用いる装置としては、特に限定されることなく、種々の翼を用いる攪拌型分散装置、高速回転せん断型分散装置、ボールミル、ビーズミル、コロイドミルなどのミル型分散装置、高圧噴射型分散装置、超音波型分散装置などを必要に応じて用いることができる。また、必要に応じて、真空または減圧下での混合・分散や温度制御下での混合・分散も行うことができる。
【００２８】
本発明において、導電助剤として用いる水スラリーのｐＨ値が７．０より大きい塩基性炭素微粒子は平均一次粒子径が１００ｎｍ以下のものが好ましく、より微細なものが好ましい。そして、この塩基性炭素微粒子は、それを単独で用いてもよいし、また、他の導電助剤、例えば、人造黒鉛、炭素繊維などと複合して用いてもよい。ただし、他の導電助剤と併用する場合、全導電助剤中において上記塩基性炭素微粒子が正極塗膜中で０．１質量％以上存在していることが好ましく、特に０．５質量％以上存在していることが好ましい。
【００２９】
本発明において、正極の主たる結合剤としては、熱可塑性樹脂、ゴム弾性を有するポリマーおよび多糖類より選ばれる少なくとも１種を用いることができ、具体的には、例えば、ポリテトラフルオロエチレン、ポリフッ化ビニリデン、ポリエチレン、ポリプロピレン、エチレン−プロピレン−ジエン共重合樹脂、スチレンブタジエンゴム、ポリブタジエン、フッ素ゴム、ポリエチレンオキシド、ポリビニルピロリドン、ポリエステル樹脂、アクリル樹脂、フェノール樹脂、エポキシ樹脂、ポリビニルアルコール、ヒドロキシプロピルセルロース樹脂などを用いることができる。それらの中でも、特にポリフッ化ビニリデンが好ましく、このポリフッ化ビニリデンを正極の主たる結合剤として用いることにより、本発明の効果を最も顕著に発現させることができる。
【００３０】
本発明において、正極活物質としては、特に限定されることはないが、例えば、ＬｉＣｏＯ２ などのリチウムコバルト酸化物、ＬｉＭｎ２ Ｏ４ などのリチウムマンガン酸化物、ＬｉＮｉＯ２ などのリチウムニッケル酸化物、二酸化マンガン、五酸化バナジウム、クロム酸化物などの金属酸化物またはそれらを基本構造とする複合酸化物（例えば、異種金属添加品）、あるいは二硫化チタン、二硫化モリブデンなどの金属硫化物などを単独でまたは２種以上の混合物として、あるいはそれらの固溶体として用いることができる。また、ＬｉＭＯ２ あるいは、ＬｉＭ２ Ｏ４ において、Ｍが、Ｃｏ、Ｎｉ、Ｍｎ、Ｆｅ、Ｃｕなどの金属元素を少なくとも１つ以上を含んでリチウム含有金属酸化物であっても特に問題はない。特にＬｉＮｉＯ２ 、ＬｉＣｏＯ２ 、ＬｉＭｎ２ Ｏ４ などの充電時の開路電圧がＬｉ基準で４Ｖ以上を示すリチウム複合酸化物を正極活物質として用いる場合には、高エネルギー密度が得られるので好ましい。
【００３１】
正極の作製にあたって、その方法は特に限定されることはないが、例えば、上記正極活物質、導電助剤、結合剤を含むペースト状の正極塗料を正極集電体としての作用を兼ねる導電性基体に塗布し、乾燥して、塗膜を形成し、必要に応じて圧縮する工程を経由することによって作製される。
【００３２】
本発明において、上記正極用の導電性基体の厚さとしては、５〜６０μｍが好ましく、特に８〜４０μｍが好ましい。また、正極塗膜の厚さとしては、片面当たり３０〜３００μｍが好ましく、特に５０〜１５０μｍが好ましい。
【００３３】
負極に用いる材料としては、リチウムイオンをドープ・脱ドープできるものであればよく、本発明においては、そのようなリチウムイオンをドープ・脱ドープできる物質を負極活物質という。そして、この負極活物質としては、特に限定されることはないが、例えば、黒鉛、熱分解炭素類、コークス類、ガラス状炭素類、有機高分子化合物の焼成体、メソカーボンマイクロビーズ、炭素繊維、活性炭などの炭素材料、Ｓｉ、Ｓｎ、Ｉｎなどの合金またはＬｉに近い低電位で充放電できるＳｉ、Ｓｎ、Ｉｎなどの酸化物などを用いることができる。
【００３４】
負極は、例えば、上記負極活物質に、例えばポリフッ化ビニリデンやポリテトラフルオロエチレンなどの結合剤を適宜添加し、さらに要すれば導電助剤を適宜添加して、溶剤でペースト状の負極塗料を調製し（結合剤はあらかじめ溶剤に溶解または分散させておいてから負極活物質などと混合してもよい）、その負極塗料を負極集電体としての作用を兼ねる導電性基体に塗布し、乾燥して負極塗膜を形成し、必要に応じて圧縮する工程を経由することによって作製される。ただし、負極の作製方法は、上記例示の方法に限定されることはない。
【００３５】
本発明において、上記負極用の導電性基体の厚さとしては、５〜６０μｍが好ましく、特に８〜４０μｍが好ましい。また、上記負極塗膜の厚さとしては、片面当たり３０〜３００μｍが好ましく、特に５０〜１５０μｍが好ましい。
【００３６】
上記導電性基体としては、例えば、アルミニウム、銅、ニッケル、ステンレス鋼などの金属の箔、エキスパンドメタル、網などが用いられるが、正極用の導電性基体としては特にアルミニウム箔が好ましく、負極用の導電性基体としては特に銅箔が好ましい。
【００３７】
上記正極や負極の作製にあたって、上記正極塗料や負極塗料を導電性基体に塗布する際の塗布方法としては、例えば、押し出しコーター、リバースローラー、ドクターブレードなどをはじめ、各種の塗布方法を採用することができる。
【００３８】
本発明の電解質としては、通常、液状電解質（以下、これを「電解液」という）が用いられる。そして、その電解液としては有機溶媒に溶質を溶解させた有機溶媒系の非水電解液が用いられる。その非水電解液の溶媒としては、特に限定されることはないが、鎖状エステルを主溶媒として用いることが特に適している。そのような鎖状エステルとしては、例えば、ジエチルカーボネート、ジメチルカーボネート、メチルエチルカーボネート、酢酸エチル、プロピオン酸メチルなどの鎖状のＣＯＯ−結合を有する有機溶媒が挙げられる。この鎖状エステルが電解液の主溶媒であるということは、これらの鎖状エステルが全電解液溶媒中の５０体積％より多い体積を占めることを意味しており、特に鎖状エステルが全電解液溶媒中の６５体積％以上が好ましい。
【００３９】
ただし、電解液溶媒としては、上記鎖状エステルのみで構成するよりも、電池容量の向上をはかるために、上記鎖状エステルに誘電率の高いエステル（誘電率３０以上のエステル）を混合して用いることが好ましい。そのような誘電率の高いエステルの全電解液溶媒中で占める量としては、１０体積％以上、特に２０体積％以上が好ましい。
【００４０】
上記誘電率の高いエステルとしては、例えば、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネート、γ−ブチロラクトン、エチレングリコールサルファイトなどが挙げられ、特にエチレンカーボネート、プロピレンカーボネートなどの環状構造のものが好ましく、とりわけ環状のカーボネートが好ましく、具体的にはエチレンカーボネートが最も好ましい。
【００４１】
また、上記誘電率の高いエチレン以外に併用可能な溶媒としては、例えば、１，２−ジメトキシエタン、１，３−ジオキソラン、テトラヒドロフラン、２−メチル−テトラヒドロフラン、ジエチルエーテルなどが挙げられる。そのほか、アミン系またはイミド系有機溶媒や、含イオウ系または含フッ素系有機溶媒なども用いることができる。
【００４２】
電解液の溶質としては、例えば、ＬｉＣｌＯ４ 、ＬｉＰＦ６ 、ＬｉＢＦ４ 、ＬｉＡｓＦ６ 、ＬｉＳｂＦ６ 、ＬｉＣＦ３ ＳＯ３ 、ＬｉＣ４ Ｆ９ ＳＯ３ 、ＬｉＣＦ３ ＣＯ２ 、Ｌｉ２ Ｃ２ Ｆ４ （ＳＯ３ ）２ 、ＬｉＮ（ＣＦ３ ＳＯ２ ）２ 、ＬｉＣ（ＣＦ３ ＳＯ２ ）３ 、ＬｉＣｎ Ｆ２ｎ＋１ＳＯ３ （ｎ≧２）などが単独でまたは２種以上混合して用いられる。特にＬｉＰＦ６ やＬｉＣ４ Ｆ９ ＳＯ３ などが、充放電特性が良好なことから好ましい。電解液中におけるリチウム塩の濃度は、特に限定されるものではないが、０．３〜１．７ｍｏｌ／ｌが好ましく、特に０．４〜１．５ｍｏｌ／ｌが好ましい。
【００４３】
本発明において、電解質としては、上記電解液以外にも、ゲル状または固体状の電解質を用いることができる。ゲル状電解質としては、上記電解液（液状電解質）をポリマーなどのゲル化剤でゲル状にしたものが用いられ、固体電解質としては、無機固体電解質のほか、ポリエチレンオキサイド、ポリプロピレンオキサイドまたはそれらの誘導体などを主材にした有機固体電解質などを用いることができる。
【００４４】
本発明のセパレータには、例えば不織布や微孔性フィルムが用いられる。上記不織布材としては、ポリプロピレン、ポリエチレン、ポリエチレンテレフタレート、ポリブチレンテレフタレートなどがある。微孔性フィルム材としては、ポリプロピレン、ポリエチレン、ポリエチレン−プロピレン共重合体などがある。
【００４５】
本発明の非水二次電池は、例えば、上記のようにして作製された正極と負極との間にセパレータを介在させて重ね合わせ、それを渦巻状、楕円状、長円形状などに巻回して作製した巻回構造の電極体やそれらを積層した積層構造の電極体を、ニッケルメッキを施した鉄やステンレス鋼あるいはアルミニウムまたはアルミニウム合金製の電池ケースや金属ラミネートフィルム内に挿入し、封口する工程を経て作製される。また、上記のように電池ケースを用いる電池では、通常、電池内部に発生したガスをある一定圧力まで上昇した段階で電池外部に排出して、電池の高圧下での破裂を防止するための防爆機構が取り入れられる。
【００４６】
【実施例】
以下、本発明に関する実施例および比較例を示して、その効果を具体的に説明するが、本発明はこれに限定されることはない。なお、実施例に先立ち、実施例で用いるアニオン性高分子の合成例を合成例１〜２で示し、比較例で用いる高分子共重合体の合成例を合成例３で示す。
【００４７】
合成例１
Ｎ−ビニル−２−ピロリドン８０質量部、アクリル酸２０質量部、２，２’−アゾビス（イソブチルニトリル）１．８質量部および２−プロパノール１００質量部を混合して反応用溶液を調製した。次に窒素導入管を備えつけた反応容器に２−プロパノール１００質量部を計りこみ、窒素シールをしながら７０℃まで昇温した。そして、その反応容器に上記溶液を２時間にわたって滴下し、滴下終了後、同温度を保持しながら１４時間反応させ、反応後の溶媒をロータリーエバポレータで留去し、化学式（１）で示される側鎖を有し、かつアニオン性官能基を有する高分子としての高分子共重合体Ａを得た。この高分子共重合体Ａの質量平均分子量は４５００であった。
【００４８】
合成例２
合成例１において、反応終了後：アンモニアを吹き込んで中和した後、溶媒をエバポレータで留去して、化学式（１）で示される側鎖を有し、かつアニオン性官能基を有する高分子としての高分子共重合体Ｂを得た。この高分子共重合体Ｂの質量平均分子量は４５００であった。
【００４９】
合成例３
Ｎ−ビニル−２−ピロリドン８０質量部、アクリル酸メチル２０質量部、２，２’−アゾビス（イソブチルニトリル）１．８質量部および２−プロパノール１００質量部を混合して反応用溶液を調製し、この反応用溶液を用いた以外は、実施例１と同様にして高分子共重合体Ｃを得た。この高分子共重合体Ｃの質量平均分子量は５０００であった。
【００５０】
実施例１
正極の作製
導電助剤としてのケッチェンブラック（水スラリーのｐＨ値９．０、平均一次粒子径４０ｎｍ）を３質量部、前記合成例１で合成した高分子共重合体Ａを１．２質量部、主たる結合剤としてのポリフッ化ビニリデンを４．８質量部、Ｎ−メチル−２−ピロリドンを６０質量部および正極活物質としてのコバルト酸リチウム（平均粒径：５．５μｍ）１９１質量部を高せん断力を有する混合機で混合し、ペースト状の正極塗料を調製した。
【００５１】
そして、得られたペースト状正極塗料を７０メッシュの網を通過させて大きなものを取り除いた後、厚さ１５μｍのアルミニウム箔からなる導電性基体の両面に均一に塗布し、乾燥して正極塗膜を形成し、さらに、この塗膜を、厚さ１６６μｍに圧縮し、所定のサイズに切断した後、アルミニウム製のリード体を溶接により取り付けて、シート状の正極を得た。この正極において、正極塗膜中のアニオン性高分子としての高分子共重合体Ａの含有率は、正極塗膜１００質量部に対して、０．６質量部であった。
【００５２】
負極の作製
負極活物質としての黒鉛系炭素材料〔ただし、（００２）面の面間距離（ｄ）＝０．３３７ｎｍ、ｃ軸方向の結晶子の大きさ（Ｌｃ）＝９５．０ｎｍ、平均一次粒子径１０μｍ、純度９９．９％以上という特性を持つ炭素材料〕を１８０質量部と、ポリフッ化ビニリデン１４質量部をＮ−メチル−２−ピロリドン１９０質量部に溶解させた溶液とを混合してペースト状の負極塗料を調製した。このペーストの負極塗料を厚さ１０μｍの帯状の銅箔からなる導電性基体の両面に均一に塗布し、乾燥して負極塗膜を形成した。単位面積当たりの負極塗膜の質量は１２．０ｍｇ／ｃｍ２ であった。この帯状体を乾燥後、厚さ１７５μｍに圧縮成形し、所定のサイズに切断した後、ニッケル製のリード体の一端を溶接して取り付け、シート状の負極を得た。
【００５３】
電解液の調製
メチルエチルカーボネートとエチレンカーボネートとを体積比２：１で混合した混合溶媒に、ＬｉＰＦ６ を１．２ｍｏｌ／ｌの濃度になるように溶解して、電解液（非水液状電解質）を調製した。
【００５４】
非水二次電池の作製
上記正極および負極を熱処理後、正極および負極を厚さ２５μｍの微孔性ポリエチレンフィルムからなるセパレータを介して渦巻状に巻回し、巻回構造の電極体とした。これを袋状のアルミニウムラミネートフィルム内に挿入し、上記電解液を注入した後、真空封止を行い、その状態で３時間室温放置し、正極、負極およびセパレータに電解液を充分に含浸させて非水二次電池を作製した。
【００５５】
実施例２
実施例１における正極塗料の調製工程を、あらかじめケッチェンブラック３質量部および高分子共重合体Ａ１．２質量部をＮ−メチル−２−ピロリドン１７質量部に均一に分散させてカーボンペーストとし、これとポリフッ化ビニリデン４．８質量部、Ｎ−メチル−２−ピロリドン４３質量部およびコバルト酸リチウム１９１質量部を、高せん断力のもとで混合する工程に変更した以外は、実施例１と同様に正極を作製し、その正極を用いた以外は実施例１と同様に非水二次電池を作製した。
【００５６】
実施例３
実施例２の正極塗料の調製工程において、実施例２で用いた高分子共重合体Ａに代えて、高分子共重合体Ｂを用いた以外は、実施例２と同様に正極を作製し、その正極を用いた以外は実施例２と同様に非水二次電池を作製した。
【００５７】
実施例４
実施例２の正極塗料の調製工程において、実施例２で用いた高分子共重合体Ａに代えて、化学式（２）で示される側鎖を有し、かつアニオン性官能基を有する高分子としての特殊ポリカルボン酸高分子分散剤ホモゲノールＬ−１８（商品名：花王社製）の溶媒除去成分を用いた以外は、実施例２と同様に正極を作製し、その正極を用いた以外は実施例２と同様に非水二次電池を作製した。上記特殊ポリカルボン酸高分子の質量平均分子量は４．０×１０４ であり、側鎖を示す化学式（２）のｍ＋ｎは６であった。
【００５８】
実施例５
実施例１の正極塗料の調製工程において、高分子共重合体Ａの添加量を１．２質量部から０．１質量部に変更した以外は、実施例１と同様に正極を作製し、その正極を用いた以外は実施例１と同様に非水二次電池を作製した。この正極において、正極塗膜中の高分子共重合体Ａの含有量は、正極塗膜１００質量部に対して０．０５質量部であった。
【００５９】
実施例６
実施例１の正極塗料の調製工程において、高分子共重合体Ａの添加量を１．２質量部から２．０質量部に変更した以外は、実施例１と同様に正極を作製し、その正極を用いた以外は実施例１と同様に非水二次電池を作製した。この正極において、正極塗膜中の高分子共重合体Ａの含有量は、正極塗膜１００質量部に対して１．０質量部であった。
【００６０】
実施例７
実施例１の正極塗料の調製工程において、ケッチェンブラックをデンカブラックＨＳ−１００（水スラリーのｐＨ値は９．０〜１０．０）に変更した以外は、実施例１と同様に正極を作製し、その正極を用いた以外は実施例１と同様に非水二次電池を作製した。
【００６１】
比較例１
実施例１の正極塗料の調製工程において、高分子共重合体Ａを添加しなかった以外は、実施例１と同様に正極を作製し、その正極を用いた以外は実施例１と同様に非水二次電池を作製した。
【００６２】
比較例２
実施例１の正極塗料の調製工程において、高分子共重合体Ａを、酸成分を含まない高分子共重合体Ｃに変更した以外は、実施例１と同様に正極を作製し、その正極を用いた以外は実施例１と同様に非水二次電池を作製した。
【００６３】
比較例３
実施例１の正極塗料の調製工程において、高分子共重合体Ａを、ステアリン酸に変更した以外は、実施例１と同様に正極を作製し、その正極を用いた以外は実施例１と同様に非水二次電池を作製した。
【００６４】
比較例４
実施例１の正極塗料の調製工程において、高分子共重合体Ａを添加せず、かつ結合剤としてポリフッ化ビニリデンに代えて、カルボキシル基変性ポリフッ化ビニリデンを用いた以外は、実施例１と同様に正極を作製し、その正極を用いた以外は実施例１と同様に非水二次電池を作製した。
【００６５】
比較例５
実施例１の正極塗料の調製工程において、ケッチェンブラックをＣＢ３０５０Ｂ（三菱化学社製導電性カーボン、水スラリーのｐＨ値は７．０）に変更した以外は、実施例１と同様に正極を作製し、その正極を用いた以外は実施例１と同様に非水二次電池を作製した。
【００６６】
上記実施例１〜７および比較例１〜５の正極の塗膜密度を表１に示す。この塗膜密度は、幅１５ｃｍ、長さ３０ｃｍに切断した塗膜の面積、塗膜厚み、質量を測定し、それらの結果から計算によって求めたものである。
【００６７】
【表１】
上記実施例１〜７および比較例１〜５の電池について、次に示す条件下での充放電を行った時の放電容量およびインピーダンスの変化を測定した。その結果を表２に示す。
【００６９】
放電容量は、１Ｃの電流制限回路を設けて４．２Ｖの定電圧で充電を行い、電池の電圧が３Ｖに低下するまで放電を行ったときの容量で規定した。充放電の繰り返しによる容量の変化は、１サイクル目と３００サイクル目の放電容量を測定することによって評価した。
【００７０】
なお、放電容量の表２への表示にあたっては、比較例１の電池の１サイクル目の放電容量を１００とし、その放電容量に対する相対値（％）で表した。
【００７１】
また、インピーダンスは、放電容量の測定時と同様の条件で、ＬＣＲメーターにより１ｋＨｚにおけるインピーダンスを測定し、表２への表示にあたっては、比較例１の電池の１サイクル目のインピーダンスを１００とする相対値（％）で表した。
【００７２】
【表２】
前記表１に示すように、導電助剤としてｐＨ値が７より大きい塩基性炭素微粒子を含み、かつアニオン性高分子（すなわち、化学式（１）または化学式（２）で示される側鎖を有し、かつアニオン性官能基を有する高分子）を添加した実施例１〜７の正極は、比較例１〜５の正極に比べて、塗膜密度が高くなっていた。また、表２に示すように、実施例１〜７の電池は、比較例１〜５の電池に比べて、１サイクル目の放電容量が高く、かつ、充放電サイクルを繰り返しても、放電容量の低下は少なかった。また、内部インピーダンスに関しても、実施例１〜７の電池は、比較例１〜５の電池に比べて低くなっており、３００サイクル後の内部インピーダンスの上昇も抑えられていることがわかる。
【００７４】
また、低分子カルボン酸を用いた比較例３が実施例１より正極の塗膜密度が低く、３００サイクル後の特性も悪いことから、正極の塗膜密度を高めて、高容量化を達成し、かつサイクル特性を向上させるためには、高分子量のアニオン性官能基成分が有効であることがわかる。また、比較例４のようにアニオン性官能基成分が主たる結合剤成分中に含まれている場合は、特にサイクル特性が劣ることから、サイクル特性を向上させるためには、主たる結合剤とは別にアニオン性官能基を有する高分子を添加することが有効であることがわかる。そして、実施例３が実施例１より特性が優れていることは、高分子共重合体Ｂが解離性の高いアンモニウム塩を含むことによるものであると考えられる。
【００７５】
また、導電助剤として塩基性炭素微粒子を用いた実施例１〜７に比べて、中性カーボンを用いた比較例５が明らかに特性が劣ることから、アニオン性官能基を有する高分子と塩基性炭素微粒子との組合せが有効であることがわかる。さらに、実施例５および実施例６と比べても、実施例１は優れた電池特性を示しており、アニオン性官能基を有する高分子の添加量は、正極塗膜１００質量部に対して、０．００５質量部から１質量部であることが好ましい。
【００７６】
【発明の効果】
以上説明したように、本発明によれば、高容量で、かつサイクル特性が優れた非水二次電池を提供することができる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a non-aqueous secondary battery, and more particularly, to a non-aqueous secondary battery having high capacity and excellent cycle characteristics.
[0002]
[Prior art]
With the miniaturization of electronic devices and the spread of mobile phones, demands for secondary batteries having a high energy density are increasing. At present, high-capacity secondary batteries that meet this demand include LiCoO 2 as a positive electrode active material.2, LiNiO2, LiMn2O4Lithium-ion secondary batteries using lithium-containing composite oxides and carbon-based materials as negative electrode active materials have been commercialized. This lithium ion secondary battery has an average driving voltage as high as 3.6 V, has an average driving voltage that is about three times that of conventional nickel-cadmium batteries and nickel-metal hydride batteries, and has a carbon-based negative electrode active material. Since a material is used and a moving body involved in charge and discharge is lithium ion, a reduction in weight can be expected.
[0003]
This lithium ion secondary battery is different from a conventional non-aqueous secondary battery using lithium metal as a negative electrode, in which the above active material is dispersed in a solvent together with a binder to prepare a paste-like paint, and the paste-like paint is prepared. The paint is applied to both sides of the conductive substrate serving also as a positive electrode current collector or a negative electrode current collector, dried, and formed into a coating film containing the above active materials, and compressed as necessary. The coating density is increased to produce a strip-shaped positive electrode and a negative electrode, and the strip-shaped positive electrode and the negative electrode are spirally wound through a separator to form a spiral electrode body. A battery is constructed by inserting it into a battery can. Then, in addition to the positive electrode active material and the binder, a conductive assistant made of a carbon-based material or the like is added to the positive electrode in order to reduce impedance in the coating film.
[0004]
It is expected that demand for portable information terminal equipment will increase in the future, and demand for high-capacity and lightweight lithium-ion secondary batteries will further increase. The increase in capacity of lithium ion secondary batteries is largely due to improvements in negative electrode materials, and even now, further increase in capacity by using metal composite materials such as Si-based or Sn-based and Li-containing nitrides is being studied. However, due to swelling of the negative electrode material due to charge / discharge, capacity deterioration and safety due to charge / discharge cycles, it has not been put to practical use, and most of the current negative electrode materials are occupied by carbon-based materials, and have a theoretical capacity of 372 mAh / g. Is approaching.
[0005]
On the other hand, regarding the positive electrode active material, generally, LiCoO2, LiMnO2, LiNiO2And other lithium-containing composite oxides. The theoretical discharge capacity of each positive electrode active material is LiCoO2Is 274 mAh / g, LiMn2O4Is 148 mAh / g, LiNiO2Is 274 mAh / g. LiCoO2Has a practical discharge capacity of about 125 to 140 mAh / g, whereas LiNiO2Has a practical discharge capacity of about 160 to 200 mAh / g. Therefore, LiNiO2Is LiCoO2It is possible to increase the capacity as compared with that of LiCoO.2It is a big problem that the production cost is high and the safety is low as compared with the conventional method. LiMnO2Has a theoretical discharge capacity of 148 mAh / g, a true density of 4.0 to 4.2 g / cc, and a LiCoO2Shows a value lower than the true density of 4.9 to 5.1 g / cc. Therefore, LiMnO2Is used, the capacity per unit volume is LiCoO2Obviously worse than From these facts, LiCoO 2 is currently used as the positive electrode active material.2Is generally used, and the increase in capacity is achieved by optimizing the coating film structure.
[0006]
The positive electrode coating film is composed mainly of a positive electrode active material, a binder and a conductive auxiliary. The method for preparing this positive electrode coating film is to uniformly disperse a positive electrode active material, a binder, and a conductive auxiliary agent in a solvent to prepare a paste-like positive electrode paint, and to form a positive electrode paint on a conductive substrate made of a metal foil or the like. Is uniformly applied, and after a drying step and a compression step, a positive electrode coating film is formed on a conductive substrate which also functions as a positive electrode current collector. As described above, the increase in the capacity of the positive electrode depends on how much the positive electrode active material is contained inside the battery as long as the capacity cannot be increased with the positive electrode active material.
[0007]
The positive electrode active material density per unit volume depends on the coating film density and the positive electrode active material content in the coating film. The coating density can be increased by increasing the pressure in the compression process. However, in such a case, the high pressure may cause the current collector of the positive electrode to break and the permeability of the electrolyte (liquid electrolyte) into the coating to decrease. There is a concern, which may lead to a decrease in productivity and deterioration in battery characteristics. On the other hand, an increase in the active material content in the positive electrode coating film is accompanied by a decrease in the amount of the binder or the conductive auxiliary. It is extremely difficult to reduce the amount of the binder because there is a concern that the coating strength of the positive electrode and the adhesion between the coating and the conductive substrate may be reduced. In addition, since the conductive additive maintains the conductivity of the positive electrode coating film and affects the internal impedance of the battery, it is a problem how to maintain the conductivity and reduce the amount of the conductive additive.
[0008]
Therefore, in order to ensure high conductivity even when the content of the conductive aid is reduced, graphite particles having a high specific surface area have been used as a measure for improving the conductive aid (Patent Document 1). And a method using a combination of a large particle size graphite powder and a small particle size acetylene black powder (see Patent Document 2).
[0009]
[Patent Document 1]
JP-A-10-144320 (page 1)
[0010]
[Patent Document 2]
JP 2000-277095 A (page 2)
[0011]
However, when graphite particles having a high specific surface area are used as a conductive additive, as in Patent Document 1, graphite having a high specific surface area has a large so-called oil absorption amount, so that a large amount of solvent is required in the formation of a coating material, and dispersion is required. Efficiency does not improve as expected. Also, as in Patent Document 2, when a large particle size graphite powder and a small particle size acetylene black powder are used in combination, the small particle size acetylene black powder has a high specific surface area. Had a similar problem. The inclusion of undispersed carbon powder also causes a decrease in the coating density.
[0012]
Therefore, various dispersants for highly dispersing carbon powder in a liquid have been proposed. For example, a block copolymer of a styrene-based copolymer and an acrylate-based copolymer (see Patent Document 3), and a copolymer of an olefin or an aromatic alkenyl compound with an ethylenically unsaturated carboxylic acid or an anhydride thereof. A water-soluble salt (see Patent Document 4), a (meth) acrylic acid-based or maleic acid-based copolymer having a polyoxyalkylene chain (see Patent Document 5), and the like have been proposed.
[0013]
[Patent Document 3]
JP-A-6-148927 (page 2)
[0014]
[Patent Document 4]
JP-A-8-239361 (page 2)
[0015]
[Patent Document 5]
JP-A-11-286644 (page 2)
[0016]
However, even with these dispersants, when carbon particles having a small particle size are dispersed in a positive electrode paint of a non-aqueous secondary battery such as a lithium ion secondary battery, none of them has sufficient dispersibility. .
[0017]
[Problems to be solved by the invention]
An object of the present invention is to solve the problems of the conventional non-aqueous secondary battery as described above, and to provide a non-aqueous secondary battery having high capacity and excellent cycle characteristics.
[0018]
[Means for Solving the Problems]
The present invention uses a basic carbon fine particle having a pH value of a water slurry of more than 7.0 as a conductive auxiliary agent of a positive electrode, and uses a side represented by the following chemical formula (1) or (2) in addition to a main binder. By using a polymer having a chain and having an anionic functional group, it has been found that it is possible to increase the density of a coating material and to form a positive electrode coating film having a high positive electrode active material content. Is solved.
Embedded image
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the reason why the present invention can provide a non-aqueous secondary battery having high capacity and excellent cycle characteristics by employing the above configuration will be described, and the configuration will be described in detail.
[0020]
In order to improve the dispersibility of the carbon fine particles used as the conductive additive in the positive electrode paint, it is important to select a dispersant. The amount of the functional group on the surface of the carbon fine particles is very small as compared with the oxide fine particles and the like, and a sufficient adsorption layer cannot be formed with a normal low-molecular type surfactant. However, if a polymer dispersant having a large number of adsorption anchors in one molecule is used as a dispersant, a sufficient adsorption layer can be formed on the surface of carbon fine particles having a low active surface with a low functional group density. In particular, the specific surface area, which is poor in dispersibility, is 100 m2Since most of the carbon fine particles having a fine particle diameter of / g or more have a basic surface, an anionic functional group is effective as an adsorption anchor.
[0021]
Further, lithium cobalt oxide (LiCoO) widely used as a positive electrode active material is used.2Etc.) have a basic surface. Therefore, when the carbon fine particles of the conductive aid have a basic surface, the active material and the conductive aid repel each other due to electrostatic repulsion, so that high-density filling is difficult. However, an adsorption layer of a polymer having a side chain represented by the chemical formula (1) or (2) on the surface of the carbon fine particles and having an anionic functional group (hereinafter simply referred to as “anionic polymer”) When this is formed, the anionic polymer is also adsorbed on the surface of the active material, and the carbon fine particles of the conductive additive and the active material particles are physically brought close to each other, thereby realizing high density of the coating film.
[0022]
In the present invention, the anionic polymer, that is, the polymer having a side chain represented by the chemical formula (1) or (2) and having an anionic functional group includes, for example, acrylic acid and maleic acid. A polymer obtained by copolymerizing an acid or the like is suitable. These carboxylic acid moieties may be partially or entirely neutralized in the form of a metal salt, an ammonium salt, or the like. Has a high degree of dissociation, so that it has a strong adsorptive power to carbon fine particles and is more excellent in dispersibility.
[0023]
The effect of the addition of the anionic polymer on battery characteristics is remarkably exhibited when a positive electrode coating film is prepared with a smaller amount of the conductive additive. That is, it is effective in producing a positive electrode coating film having a high density and a high active material ratio. Specifically, the density of the positive electrode coating film is 3.25 g / cm.3The above case is effective when the ratio of the positive electrode active material in the positive electrode coating film is 94 parts by mass or more based on 100 parts by mass of the positive electrode coating film.
[0024]
The anionic polymer used in the present invention has a mass average molecular weight (hereinafter sometimes abbreviated to “molecular weight Mw”) of 2.0 × 103~ 1.5 × 106Is preferred. The molecular weight Mw of the anionic polymer is 2.0 × 103If it is smaller, the amount of adsorption to the conductive aid is small, and the dispersion of the conductive aid will be insufficient, and the molecular weight Mw of the anionic polymer will be 1.5 × 106If it is larger, conductivity may be hindered due to the thick adsorption layer, or agglomeration may occur to lower the conductivity.
[0025]
In the present invention, it is preferable that 0.005 parts by mass to 1 part by mass of the anionic polymer is added to 100 parts by mass of the positive electrode coating film so as to be contained in the positive electrode coating film. When the content of the anionic polymer is less than 0.005 parts by mass with respect to 100 parts by mass of the positive electrode coating film, the effect of adding the anionic polymer is not sufficiently exhibited, and when the content is more than 1 part by mass. However, since the insulating polymer increases in the positive electrode coating film, the impedance of the battery may be increased, and the battery characteristics may be degraded.
[0026]
In the present invention, there is no particular limitation on the method for incorporating the anionic polymer into the positive electrode paint. The positive electrode paint is prepared by mixing and dispersing the positive electrode active material with a binder, a conductive auxiliary, and an organic solvent. The anionic polymer may be added when mixing the positive electrode active material, the conductive additive, and the main binder. Also, a method of adding an anionic polymer when preparing a dispersion of a conductive assistant and an organic solvent in advance, then adding a main binder and a positive electrode active material, and adopting a method of passing through a step of preparing a positive electrode paint is adopted. This method is most effective. Further, the conductive assistant and the anionic polymer may be mixed and dispersed in a solvent-free state, and then a main binder, a solvent, a positive electrode active material and the like may be added to prepare a positive electrode paint. When a plurality of materials are used as the conductive additive, a dispersion is prepared in advance with the basic carbon fine particles used as an essential component, an anionic polymer, and an organic solvent, and then, other conductive additives, a main binder, and a positive electrode active material are prepared. A method of adding a substance or the like and passing through a step of preparing a positive electrode paint can also be adopted. As the organic solvent, for example, one or a mixture of two or more aprotic organic solvents such as N-methyl-2-pyrrolidone, dimethylacetamide, and dimethylformamide can be used.
[0027]
The apparatus used for mixing and dispersing is not particularly limited, and is a stirring type dispersing apparatus using various blades, a high-speed rotary shearing type dispersing apparatus, a mill type dispersing apparatus such as a ball mill, a bead mill, a colloid mill, and a high-pressure injection. A dispersing device, an ultrasonic dispersing device, or the like can be used as necessary. If necessary, mixing / dispersion under vacuum or reduced pressure or mixing / dispersion under temperature control can also be performed.
[0028]
In the present invention, the basic carbon fine particles having a pH value of the water slurry used as the conductive additive of greater than 7.0 preferably have an average primary particle diameter of 100 nm or less, and more preferably finer particles. The basic carbon fine particles may be used alone, or may be used in combination with another conductive aid, for example, artificial graphite, carbon fiber, or the like. However, when used in combination with other conductive aids, the basic carbon fine particles are preferably present in the positive electrode coating film in an amount of 0.1% by mass or more, particularly 0.5% by mass or more in all the conductive assistants. Preferably it is present.
[0029]
In the present invention, as a main binder of the positive electrode, at least one selected from a thermoplastic resin, a polymer having rubber elasticity, and a polysaccharide can be used. Specifically, for example, polytetrafluoroethylene, polyfluorinated Vinylidene, polyethylene, polypropylene, ethylene-propylene-diene copolymer resin, styrene butadiene rubber, polybutadiene, fluoro rubber, polyethylene oxide, polyvinyl pyrrolidone, polyester resin, acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol, hydroxypropyl cellulose resin, etc. Can be used. Among them, polyvinylidene fluoride is particularly preferred. By using this polyvinylidene fluoride as a main binder of the positive electrode, the effects of the present invention can be most remarkably exhibited.
[0030]
In the present invention, the positive electrode active material is not particularly limited.2Such as lithium cobalt oxide, LiMn2O4Such as lithium manganese oxide, LiNiO2Metal oxides such as lithium nickel oxide, manganese dioxide, vanadium pentoxide, and chromium oxide or composite oxides having these as the basic structure (for example, products with different types of metals), titanium disulfide, molybdenum disulfide, etc. Can be used alone or as a mixture of two or more thereof, or as a solid solution thereof. Also, LiMO2Alternatively, LiM2O4In the above, there is no particular problem even if M is a lithium-containing metal oxide containing at least one metal element such as Co, Ni, Mn, Fe, and Cu. Especially LiNiO2, LiCoO2, LiMn2O4It is preferable to use a lithium composite oxide having an open circuit voltage of 4 V or more based on Li as a positive electrode active material during charging, because a high energy density can be obtained.
[0031]
The method for producing the positive electrode is not particularly limited. For example, a paste-like positive electrode paint containing the above-mentioned positive electrode active material, conductive auxiliary agent, and binder is used as a conductive base material that also functions as a positive electrode current collector. And dried to form a coating film and, if necessary, through a step of compression.
[0032]
In the present invention, the thickness of the conductive substrate for the positive electrode is preferably 5 to 60 μm, and particularly preferably 8 to 40 μm. Further, the thickness of the positive electrode coating film is preferably 30 to 300 μm, more preferably 50 to 150 μm per side.
[0033]
The material used for the negative electrode may be any material capable of doping and undoping lithium ions. In the present invention, such a material capable of doping and undoping lithium ions is referred to as a negative electrode active material. The negative electrode active material is not particularly limited. For example, graphite, pyrolytic carbons, cokes, glassy carbons, fired bodies of organic polymer compounds, mesocarbon microbeads, carbon fibers Alternatively, a carbon material such as activated carbon, an alloy such as Si, Sn, or In, or an oxide such as Si, Sn, or In that can be charged and discharged at a low potential close to Li can be used.
[0034]
For the negative electrode, for example, a binder such as polyvinylidene fluoride or polytetrafluoroethylene is appropriately added to the negative electrode active material, and if necessary, a conductive auxiliary is appropriately added. Prepared (the binder may be dissolved or dispersed in a solvent in advance and then mixed with the negative electrode active material, etc.), and the negative electrode paint is applied to a conductive substrate also serving as a negative electrode current collector, and dried. To form a negative electrode coating film and, if necessary, passing through a step of compressing. However, the method for manufacturing the negative electrode is not limited to the method described above.
[0035]
In the present invention, the thickness of the conductive substrate for the negative electrode is preferably 5 to 60 μm, and particularly preferably 8 to 40 μm. Further, the thickness of the negative electrode coating film is preferably 30 to 300 μm, more preferably 50 to 150 μm per one side.
[0036]
As the conductive substrate, for example, aluminum, copper, nickel, metal foils such as stainless steel, expanded metal, nets and the like are used, and as the conductive substrate for the positive electrode, aluminum foil is particularly preferable, and for the negative electrode, A copper foil is particularly preferred as the conductive substrate.
[0037]
In producing the positive electrode and the negative electrode, as a method of applying the positive electrode paint or the negative electrode paint to the conductive substrate, for example, an extrusion coater, a reverse roller, a doctor blade, and the like, various application methods may be employed. Can be.
[0038]
As the electrolyte of the present invention, a liquid electrolyte (hereinafter, referred to as “electrolyte solution”) is generally used. As the electrolyte, an organic solvent-based nonaqueous electrolyte in which a solute is dissolved in an organic solvent is used. The solvent of the non-aqueous electrolyte is not particularly limited, but it is particularly suitable to use a chain ester as a main solvent. Examples of such a chain ester include organic solvents having a chain COO-bond, such as diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, ethyl acetate, and methyl propionate. The fact that the chain ester is the main solvent of the electrolytic solution means that the chain ester occupies more than 50% by volume of the total electrolyte solvent, and in particular, the chain ester is The content is preferably 65% by volume or more in the liquid solvent.
[0039]
However, in order to improve the battery capacity as compared with the case where only the chain ester is used as the electrolyte solution solvent, the chain ester is mixed with an ester having a high dielectric constant (an ester having a dielectric constant of 30 or more). Preferably, it is used. The amount of the ester having such a high dielectric constant in the total electrolyte solution solvent is preferably at least 10% by volume, particularly preferably at least 20% by volume.
[0040]
Examples of the ester having a high dielectric constant include, for example, ethylene carbonate, propylene carbonate, butylene carbonate, γ-butyrolactone, ethylene glycol sulfite, and the like. Is preferred, and specifically, ethylene carbonate is most preferred.
[0041]
Examples of the solvent that can be used in combination with ethylene having a high dielectric constant include 1,2-dimethoxyethane, 1,3-dioxolan, tetrahydrofuran, 2-methyl-tetrahydrofuran, and diethyl ether. In addition, an amine-based or imide-based organic solvent, a sulfur-containing or fluorine-containing organic solvent, and the like can also be used.
[0042]
As the solute of the electrolytic solution, for example, LiClO4, LiPF6, LiBF4, LiAsF6, LiSbF6, LiCF3SO3, LiC4F9SO3, LiCF3CO2, Li2C2F4(SO3)2, LiN (CF3SO2)2, LiC (CF3SO2)3, LiCnF2n + 1SO3(N ≧ 2) may be used alone or in combination of two or more. Especially LiPF6And LiC4F9SO3And the like are preferable because of good charge / discharge characteristics. The concentration of the lithium salt in the electrolytic solution is not particularly limited, but is preferably from 0.3 to 1.7 mol / l, particularly preferably from 0.4 to 1.5 mol / l.
[0043]
In the present invention, as the electrolyte, a gel or solid electrolyte can be used in addition to the above-mentioned electrolyte. As the gel electrolyte, those obtained by gelling the above electrolytic solution (liquid electrolyte) with a gelling agent such as a polymer are used. As the solid electrolyte, in addition to inorganic solid electrolytes, polyethylene oxide, polypropylene oxide or derivatives thereof. For example, an organic solid electrolyte mainly composed of such materials can be used.
[0044]
For the separator of the present invention, for example, a nonwoven fabric or a microporous film is used. Examples of the nonwoven fabric material include polypropylene, polyethylene, polyethylene terephthalate, and polybutylene terephthalate. Examples of the microporous film material include polypropylene, polyethylene, and polyethylene-propylene copolymer.
[0045]
The non-aqueous secondary battery of the present invention is, for example, superposed with a separator interposed between the positive electrode and the negative electrode manufactured as described above, and wound in a spiral, elliptical, oval, or the like. The spirally wound electrode body and the laminated electrode body obtained by laminating them are inserted into a battery case or a metal laminated film made of nickel-plated iron, stainless steel or aluminum or an aluminum alloy, and sealed. It is produced through a process. Also, in a battery using a battery case as described above, gas generated inside the battery is discharged to the outside of the battery when the pressure has risen to a certain pressure, and explosion-proof for preventing the battery from bursting under high pressure. A mechanism is adopted.
[0046]
【Example】
Hereinafter, the effects of the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto. Prior to Examples, Synthesis Examples 1 and 2 show synthesis examples of anionic polymers used in Examples, and Synthesis Example 3 show synthesis examples of polymer copolymers used in Comparative Examples.
[0047]
Synthesis Example 1
80 parts by mass of N-vinyl-2-pyrrolidone, 20 parts by mass of acrylic acid, 1.8 parts by mass of 2,2'-azobis (isobutylnitrile) and 100 parts by mass of 2-propanol were mixed to prepare a reaction solution. Next, 100 parts by mass of 2-propanol was weighed into a reaction vessel equipped with a nitrogen inlet tube, and the temperature was raised to 70 ° C. while sealing with nitrogen. Then, the solution is dropped into the reaction vessel over 2 hours, and after completion of the dropping, the mixture is reacted for 14 hours while maintaining the same temperature. The solvent after the reaction is distilled off by a rotary evaporator, and the solvent represented by the chemical formula (1) is removed. A polymer copolymer A as a polymer having a chain and having an anionic functional group was obtained. The weight average molecular weight of this polymer copolymer A was 4,500.
[0048]
Synthesis Example 2
In Synthesis Example 1, after completion of the reaction: after neutralization by blowing ammonia, the solvent was distilled off by an evaporator to obtain a polymer having a side chain represented by the chemical formula (1) and having an anionic functional group. Was obtained. The weight average molecular weight of this polymer copolymer B was 4,500.
[0049]
Synthesis Example 3
A reaction solution was prepared by mixing 80 parts by mass of N-vinyl-2-pyrrolidone, 20 parts by mass of methyl acrylate, 1.8 parts by mass of 2,2′-azobis (isobutylnitrile) and 100 parts by mass of 2-propanol. A polymer copolymer C was obtained in the same manner as in Example 1 except that this reaction solution was used. The weight average molecular weight of this polymer copolymer C was 5,000.
[0050]
Example 1
Preparation of positive electrode
3 parts by mass of Ketjen Black (pH value of water slurry: 9.0, average primary particle diameter: 40 nm) as a conductive auxiliary agent, 1.2 parts by mass of polymer copolymer A synthesized in Synthesis Example 1 above, mainly 4.8 parts by mass of polyvinylidene fluoride as a binder, 60 parts by mass of N-methyl-2-pyrrolidone, and 191 parts by mass of lithium cobalt oxide (average particle size: 5.5 μm) as a positive electrode active material were subjected to high shearing force. And a paste-like positive electrode paint was prepared.
[0051]
Then, the obtained paste-like positive electrode paint is passed through a 70-mesh net to remove large pieces, and then uniformly applied to both sides of a conductive substrate made of an aluminum foil having a thickness of 15 μm, dried, and dried. Further, the coating film was compressed to a thickness of 166 μm, cut into a predetermined size, and then an aluminum lead was attached by welding to obtain a sheet-shaped positive electrode. In this positive electrode, the content of the polymer copolymer A as the anionic polymer in the positive electrode coating film was 0.6 parts by mass with respect to 100 parts by mass of the positive electrode coating film.
[0052]
Fabrication of negative electrode
Graphite-based carbon material as negative electrode active material [however, interplanar distance (d) of (002) plane = 0.337 nm, crystallite size (Lc) in c-axis direction = 95.0 nm, average primary particle diameter 10 μm 180 parts by mass of a carbon material having a characteristic of purity of 99.9% or more] and a solution obtained by dissolving 14 parts by mass of polyvinylidene fluoride in 190 parts by mass of N-methyl-2-pyrrolidone. A negative electrode paint was prepared. A negative electrode paint of this paste was uniformly applied to both sides of a conductive substrate made of a strip-shaped copper foil having a thickness of 10 μm, and dried to form a negative electrode coating film. The mass of the negative electrode coating per unit area is 12.0 mg / cm2Met. After drying this band, it was compression-molded to a thickness of 175 μm, cut into a predetermined size, and then attached by welding one end of a nickel lead body to obtain a sheet-shaped negative electrode.
[0053]
Preparation of electrolyte
LiPF was added to a mixed solvent obtained by mixing methyl ethyl carbonate and ethylene carbonate at a volume ratio of 2: 1.6Was dissolved to a concentration of 1.2 mol / l to prepare an electrolytic solution (non-aqueous liquid electrolyte).
[0054]
Fabrication of non-aqueous secondary batteries
After heat treatment of the positive electrode and the negative electrode, the positive electrode and the negative electrode were spirally wound through a separator made of a microporous polyethylene film having a thickness of 25 μm to obtain a wound electrode body. This is inserted into a bag-shaped aluminum laminate film, and after the above-mentioned electrolyte solution is injected, vacuum sealing is performed, and then left at room temperature for 3 hours in this state, and the positive electrode, the negative electrode and the separator are sufficiently impregnated with the electrolyte solution. A non-aqueous secondary battery was manufactured.
[0055]
Example 2
In the preparation process of the positive electrode paint in Example 1, 3 parts by mass of Ketjen Black and 1.2 parts by mass of the polymer copolymer A were previously uniformly dispersed in 17 parts by mass of N-methyl-2-pyrrolidone to form a carbon paste, Example 1 was repeated except that 4.8 parts by mass of polyvinylidene fluoride, 43 parts by mass of N-methyl-2-pyrrolidone, and 191 parts by mass of lithium cobaltate were mixed under a high shearing force. A positive electrode was prepared in the same manner, and a non-aqueous secondary battery was prepared in the same manner as in Example 1 except that the positive electrode was used.
[0056]
Example 3
In the preparation process of the positive electrode paint of Example 2, a positive electrode was prepared in the same manner as in Example 2, except that the polymer copolymer B was used instead of the polymer copolymer A used in Example 2, A non-aqueous secondary battery was produced in the same manner as in Example 2 except that the positive electrode was used.
[0057]
Example 4
In the preparation process of the positive electrode paint of Example 2, instead of the polymer copolymer A used in Example 2, a polymer having a side chain represented by the chemical formula (2) and having an anionic functional group was used. A positive electrode was prepared in the same manner as in Example 2 except that the solvent removing component of the special polycarboxylic acid polymer dispersant Homogenol L-18 (trade name: manufactured by Kao Corporation) was used. A non-aqueous secondary battery was produced in the same manner as in Example 2. The mass average molecular weight of the special polycarboxylic acid polymer is 4.0 × 104And m + n in Chemical Formula (2) representing a side chain was 6.
[0058]
Example 5
In the preparation process of the positive electrode paint of Example 1, a positive electrode was prepared in the same manner as in Example 1 except that the addition amount of the polymer copolymer A was changed from 1.2 parts by mass to 0.1 part by mass. A non-aqueous secondary battery was produced in the same manner as in Example 1 except that the positive electrode was used. In this positive electrode, the content of the polymer copolymer A in the positive electrode coating film was 0.05 part by mass with respect to 100 parts by mass of the positive electrode coating film.
[0059]
Example 6
In the preparation process of the positive electrode paint of Example 1, a positive electrode was prepared in the same manner as in Example 1 except that the amount of the polymer copolymer A was changed from 1.2 parts by mass to 2.0 parts by mass. A non-aqueous secondary battery was produced in the same manner as in Example 1 except that the positive electrode was used. In this positive electrode, the content of the polymer copolymer A in the positive electrode coating film was 1.0 part by mass with respect to 100 parts by mass of the positive electrode coating film.
[0060]
Example 7
A positive electrode was prepared in the same manner as in Example 1, except that Ketjen Black was changed to Denka Black HS-100 (pH value of the water slurry was 9.0 to 10.0) in the preparation process of the positive electrode paint of Example 1. Then, a non-aqueous secondary battery was produced in the same manner as in Example 1 except that the positive electrode was used.
[0061]
Comparative Example 1
In the preparation process of the positive electrode paint of Example 1, a positive electrode was prepared in the same manner as in Example 1 except that the polymer copolymer A was not added, and the same procedure as in Example 1 was carried out except that the positive electrode was used. A water secondary battery was produced.
[0062]
Comparative Example 2
In the preparation process of the positive electrode paint of Example 1, a positive electrode was prepared in the same manner as in Example 1, except that the polymer copolymer A was changed to a polymer copolymer C containing no acid component. A non-aqueous secondary battery was produced in the same manner as in Example 1 except that the battery was used.
[0063]
Comparative Example 3
A positive electrode was prepared in the same manner as in Example 1 except that the polymer copolymer A was changed to stearic acid in the preparation process of the positive electrode paint of Example 1, and the same as Example 1 except that the positive electrode was used. Then, a non-aqueous secondary battery was manufactured.
[0064]
Comparative Example 4
In the preparation process of the positive electrode paint of Example 1, the same as Example 1 except that the polymer copolymer A was not added, and instead of polyvinylidene fluoride as the binder, a carboxyl group-modified polyvinylidene fluoride was used. Then, a non-aqueous secondary battery was manufactured in the same manner as in Example 1 except that the positive electrode was used.
[0065]
Comparative Example 5
A positive electrode was prepared in the same manner as in Example 1 except that Ketjen Black was changed to CB3050B (conductive carbon manufactured by Mitsubishi Chemical Corporation, pH value of a water slurry was 7.0) in the preparation process of the positive electrode paint of Example 1. Then, a non-aqueous secondary battery was produced in the same manner as in Example 1 except that the positive electrode was used.
[0066]
Table 1 shows the coating density of the positive electrodes of Examples 1 to 7 and Comparative Examples 1 to 5. The coating film density is obtained by measuring the area, coating film thickness, and mass of a coating film cut into a width of 15 cm and a length of 30 cm, and calculating the results from the results.
[0067]
[Table 1]
With respect to the batteries of Examples 1 to 7 and Comparative Examples 1 to 5, changes in discharge capacity and impedance when charging and discharging were performed under the following conditions were measured. Table 2 shows the results.
[0069]
The discharge capacity was defined as the capacity at which a current limiting circuit of 1 C was provided, charging was performed at a constant voltage of 4.2 V, and discharging was performed until the battery voltage dropped to 3 V. The change in capacity due to repeated charge and discharge was evaluated by measuring the discharge capacity at the first cycle and the 300th cycle.
[0070]
In displaying the discharge capacity in Table 2, the discharge capacity in the first cycle of the battery of Comparative Example 1 was defined as 100, and the discharge capacity was expressed as a relative value (%) to the discharge capacity.
[0071]
The impedance was measured at 1 kHz with an LCR meter under the same conditions as those for the measurement of the discharge capacity. In displaying in Table 2, the impedance of the first cycle of the battery of Comparative Example 1 was set to 100. It was expressed as a value (%).
[0072]
[Table 2]
As shown in Table 1 above, the conductive aid contains basic carbon fine particles having a pH value of more than 7 and an anionic polymer (that is, having a side chain represented by the chemical formula (1) or (2)). And the polymer having an anionic functional group) of Examples 1 to 7 had higher coating density than the positive electrodes of Comparative Examples 1 to 5. Further, as shown in Table 2, the batteries of Examples 1 to 7 had higher discharge capacities in the first cycle than the batteries of Comparative Examples 1 to 5, and even when the charge / discharge cycle was repeated, the discharge capacities were higher. Decrease was small. Also, regarding the internal impedance, the batteries of Examples 1 to 7 are lower than the batteries of Comparative Examples 1 to 5, and it can be seen that the increase of the internal impedance after 300 cycles is suppressed.
[0074]
In Comparative Example 3 using a low-molecular carboxylic acid, the coating density of the positive electrode was lower than that of Example 1, and the characteristics after 300 cycles were poor. Therefore, the coating density of the positive electrode was increased to achieve high capacity. It can be seen that a high molecular weight anionic functional group component is effective for improving the cycle characteristics. In addition, when the anionic functional group component is contained in the main binder component as in Comparative Example 4, the cycle characteristics are particularly poor. It can be seen that it is effective to add a polymer having an anionic functional group. The reason that Example 3 is superior to Example 1 in properties is considered to be due to the fact that the polymer copolymer B contains an ammonium salt having a high dissociation property.
[0075]
Moreover, since Comparative Example 5 using neutral carbon was clearly inferior in characteristics as compared with Examples 1 to 7 using basic carbon fine particles as a conductive auxiliary, a polymer having an anionic functional group and a base were compared. It is understood that the combination with the carbon fine particles is effective. Furthermore, even in comparison with Examples 5 and 6, Example 1 shows excellent battery characteristics, and the amount of the polymer having an anionic functional group added is 100 parts by mass of the positive electrode coating film. It is preferably from 0.005 parts by mass to 1 part by mass.
[0076]
【The invention's effect】
As described above, according to the present invention, a non-aqueous secondary battery having high capacity and excellent cycle characteristics can be provided.
Claims (5)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003062701A JP4243964B2 (en) | 2003-03-10 | 2003-03-10 | Non-aqueous secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003062701A JP4243964B2 (en) | 2003-03-10 | 2003-03-10 | Non-aqueous secondary battery |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2004273281A true JP2004273281A (en) | 2004-09-30 |
| JP4243964B2 JP4243964B2 (en) | 2009-03-25 |
Family
ID=33124493
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2003062701A Expired - Fee Related JP4243964B2 (en) | 2003-03-10 | 2003-03-10 | Non-aqueous secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4243964B2 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009123523A (en) * | 2007-11-15 | 2009-06-04 | Jsr Corp | Binder composition for battery electrode, method of manufacturing the same, paste for battery electrode, battery electrode, and method of manufacturing battery electrode |
| JP2009272107A (en) * | 2008-05-07 | 2009-11-19 | Sumitomo Bakelite Co Ltd | Composition for secondary battery electrode, electrode for secondary battery, and secondary battery |
| JP2014241259A (en) * | 2013-06-12 | 2014-12-25 | 株式会社神戸製鋼所 | Current collector, method for manufacturing current collector, electrode, and secondary battery |
| JPWO2021039539A1 (en) * | 2019-08-30 | 2021-03-04 | ||
| CN112956073A (en) * | 2018-11-09 | 2021-06-11 | 株式会社理光 | Inorganic particle layer, electrode element, and nonaqueous electrolyte electricity storage element |
| CN114497444A (en) * | 2022-02-16 | 2022-05-13 | 华鼎国联四川动力电池有限公司 | Ceramic slurry for protective coating of lithium ion battery pole piece and preparation method thereof |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0696770A (en) * | 1992-09-10 | 1994-04-08 | Fuji Photo Film Co Ltd | Chemical battery |
| JPH10279608A (en) * | 1997-04-03 | 1998-10-20 | Nippon Zeon Co Ltd | Polymer, battery binder made therefrom, electrode and lithium secondary battery |
| JPH10284057A (en) * | 1997-03-31 | 1998-10-23 | Toray Ind Inc | Electrode for battery and secondary battery using the same |
| JPH11228902A (en) * | 1998-02-17 | 1999-08-24 | Elf Atochem Japan Kk | Method to adhere vinylidene fluoride resin to metalic base material, electrode structure and its preparation |
| JP2000294247A (en) * | 1999-04-12 | 2000-10-20 | Hitachi Powdered Metals Co Ltd | Negative electrode paint film of lithium ion secondary battery and lithium ion secondary battery using it |
| JP2002110169A (en) * | 2000-07-26 | 2002-04-12 | Nippon Zeon Co Ltd | Binder for electrode of lithium ion secondary battery and use of the same |
-
2003
- 2003-03-10 JP JP2003062701A patent/JP4243964B2/en not_active Expired - Fee Related
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0696770A (en) * | 1992-09-10 | 1994-04-08 | Fuji Photo Film Co Ltd | Chemical battery |
| JPH10284057A (en) * | 1997-03-31 | 1998-10-23 | Toray Ind Inc | Electrode for battery and secondary battery using the same |
| JPH10279608A (en) * | 1997-04-03 | 1998-10-20 | Nippon Zeon Co Ltd | Polymer, battery binder made therefrom, electrode and lithium secondary battery |
| JPH11228902A (en) * | 1998-02-17 | 1999-08-24 | Elf Atochem Japan Kk | Method to adhere vinylidene fluoride resin to metalic base material, electrode structure and its preparation |
| JP2000294247A (en) * | 1999-04-12 | 2000-10-20 | Hitachi Powdered Metals Co Ltd | Negative electrode paint film of lithium ion secondary battery and lithium ion secondary battery using it |
| JP2002110169A (en) * | 2000-07-26 | 2002-04-12 | Nippon Zeon Co Ltd | Binder for electrode of lithium ion secondary battery and use of the same |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009123523A (en) * | 2007-11-15 | 2009-06-04 | Jsr Corp | Binder composition for battery electrode, method of manufacturing the same, paste for battery electrode, battery electrode, and method of manufacturing battery electrode |
| JP2009272107A (en) * | 2008-05-07 | 2009-11-19 | Sumitomo Bakelite Co Ltd | Composition for secondary battery electrode, electrode for secondary battery, and secondary battery |
| JP2014241259A (en) * | 2013-06-12 | 2014-12-25 | 株式会社神戸製鋼所 | Current collector, method for manufacturing current collector, electrode, and secondary battery |
| CN112956073A (en) * | 2018-11-09 | 2021-06-11 | 株式会社理光 | Inorganic particle layer, electrode element, and nonaqueous electrolyte electricity storage element |
| US11955640B2 (en) | 2018-11-09 | 2024-04-09 | Ricoh Company, Ltd. | Inorganic particle layer, electrode, electrode element, and non-aqueous electrolyte power storage element |
| JPWO2021039539A1 (en) * | 2019-08-30 | 2021-03-04 | ||
| CN114342106A (en) * | 2019-08-30 | 2022-04-12 | 株式会社村田制作所 | Secondary battery |
| JP7392727B2 (en) | 2019-08-30 | 2023-12-06 | 株式会社村田製作所 | secondary battery |
| CN114497444A (en) * | 2022-02-16 | 2022-05-13 | 华鼎国联四川动力电池有限公司 | Ceramic slurry for protective coating of lithium ion battery pole piece and preparation method thereof |
| CN114497444B (en) * | 2022-02-16 | 2023-05-30 | 华鼎国联四川动力电池有限公司 | Ceramic slurry for lithium ion battery pole piece protective coating and preparation method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| JP4243964B2 (en) | 2009-03-25 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4878687B2 (en) | Lithium secondary battery | |
| JP4035760B2 (en) | Nonaqueous electrolyte secondary battery | |
| JP2003323895A (en) | Nonaqueous electrolyte battery | |
| JP2007317534A (en) | Non-aqueous electrolyte secondary battery | |
| JP2008166156A (en) | Storage element | |
| JP2004171901A (en) | Nonaqueous secondary battery, negative electrode therefor, manufacturing method thereof, and electronic device using nonaqueous secondary battery | |
| US11929498B2 (en) | Silicon-carbon complex and lithium secondary battery comprising the same | |
| JP4994628B2 (en) | Nonaqueous electrolyte secondary battery | |
| JP2004134207A (en) | Positive electrode active material and non-aqueous electrolyte secondary battery | |
| JP3579280B2 (en) | Negative electrode for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery provided with this negative electrode | |
| JP3580209B2 (en) | Lithium ion secondary battery | |
| JP2002087807A (en) | Multilayer graphite, manufacturing method thereof and non-aqueous electrolyte secondary battery | |
| JPH1167215A (en) | Nonaqueous electrolyte secondary battery | |
| JP4979049B2 (en) | Non-aqueous secondary battery | |
| JP4243964B2 (en) | Non-aqueous secondary battery | |
| JP4145138B2 (en) | Nonaqueous electrolyte secondary battery | |
| JP2002128526A (en) | Lithium transition metal compound oxide for positive electrode active material for lithium secondary battery and lithium secondary battery using the same | |
| JP3650548B2 (en) | Electrode active material and non-aqueous electrolyte secondary battery using the electrode active material | |
| JP4120439B2 (en) | Lithium ion secondary battery | |
| JP2004259675A (en) | Non-aqueous electrolyte secondary battery and its manufacturing method | |
| JP2002117845A (en) | Lithium iron complex oxide for lithium secondary battery positive electrode active material | |
| JP2002025626A (en) | Aging method for lithium secondary battery | |
| JP2002075330A (en) | Nonaqueous secondary battery and its manufacturing method | |
| JP2001216965A (en) | Positive electrode for lithium secondary battery | |
| JP2003272634A (en) | Nonaqueous secondary battery |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20050518 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20080815 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20080911 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20081224 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20081224 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 4243964 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120116 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120116 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120116 Year of fee payment: 3 |
|
| S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R313111 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120116 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120116 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120116 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120116 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130116 Year of fee payment: 4 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130116 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130116 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130116 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140116 Year of fee payment: 5 |
|
| S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R313111 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140116 Year of fee payment: 5 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140116 Year of fee payment: 5 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| S531 | Written request for registration of change of domicile |
Free format text: JAPANESE INTERMEDIATE CODE: R313531 |
|
| S533 | Written request for registration of change of name |
Free format text: JAPANESE INTERMEDIATE CODE: R313533 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| LAPS | Cancellation because of no payment of annual fees |