JP3716830B2 - Method for producing negative electrode material for lithium ion secondary battery - Google Patents
Method for producing negative electrode material for lithium ion secondary battery Download PDFInfo
- Publication number
- JP3716830B2 JP3716830B2 JP2002344805A JP2002344805A JP3716830B2 JP 3716830 B2 JP3716830 B2 JP 3716830B2 JP 2002344805 A JP2002344805 A JP 2002344805A JP 2002344805 A JP2002344805 A JP 2002344805A JP 3716830 B2 JP3716830 B2 JP 3716830B2
- Authority
- JP
- Japan
- Prior art keywords
- negative electrode
- electrode material
- binder
- pitch
- graphite powder
- 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.)
- Expired - Fee Related
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
Landscapes
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Carbon And Carbon Compounds (AREA)
Description
【０００１】
【技術分野】
本発明は、リチウムイオン二次電池用負極材の製造方法に関し、より詳しくは略球状に造粒した黒鉛粉末にバインダ−ピッチを被覆・含浸して、焼成および黒鉛化して得られる高容量で容量ロスが少なく、かつ充填密度が高い負極材の製造方法に関する。
【０００２】
【従来の技術】
近年、リチウム二次電池はハイパワ−、高容量の二次電池として携帯電話、パソコン等の可搬型機器類に多く使用され、今後も需要がさらに高まると予想されている。
【０００３】
このような可搬型機器類の小型化への流れを受けて、リチウム二次電池も小型化、軽量化またさらなる高性能化への要請が強まっている。
【０００４】
そのため、リチウム二次電池を構成するパ−ツや材料も高性能化の動きが活発になっており、中でも負極材は電池の性能を左右するものとしてその重要性が高まっている。
【０００５】
この負極材としてカ−ボン系材料が注目されている。
カ−ボン系負極材に要求される特性としては、まず放電容量が高容量であること、また容量ロスの低減が基本的に重要であるが、これらのみにとどまらず、電池内に多量の負極材を充填できるよう充填密度の高いこと、また急速充放電性も要求されている。
【０００６】
従来よりこのような負極材に天然黒鉛、人造黒鉛が用いられてきたが、上記のような特性を何れも満足させる材料は未だ上市されていない。
【０００７】
まず、放電容量が高い材料としては天然黒鉛が挙げられ、理論値の３７２ｍＡｈ／ｇに近い容量を得ることができる。
しかし、天然黒鉛は高容量化の面では優れているが、基本的に形状が球状ではなく扁平であることに起因する欠点がある。
【０００８】
即ち、粉砕した天然黒鉛は、鱗片状あるいは鱗状であり、初期放電容量は大きいが、扁平な形状のために集電体の銅箔と並行に粒子が配向するので、リチウムイオンの吸蔵・放出による負極の体積膨張・収縮が大きくサイクル特性の劣化が重要な欠点となる。
また扁平な形状のため充填密度も高くない。
【０００９】
そして天然黒鉛は、単に粉砕・整粒しただけでは不純物を１０〜１５％と多く含み、産地や鉱床によって不純物の成分や量にばらつきがある。
このため、電池用途に使用した場合、天然黒鉛使用量に対する放電容量の効率や安全性の問題を考慮すると、脱灰処理を施し不純物を０．２％以下にする必要があり、不純物除去のため製造コストが増加する。
なお、天然黒鉛の一種として土状黒鉛があるが、結晶の発達が不良のため、鱗状、鱗片状の天然黒鉛に比べて、低容量の負極材しか得られないので好ましくない。
【００１０】
そこで、天然黒鉛の放電容量における優れた特性を生かしつつ、その欠点を解消する試みもなされている。
天然黒鉛塊を特殊な方法で略球状になるように粉砕した材料や、鱗片状や鱗状の天然黒鉛粉末を適当なバインダ−を用いて、略球状に賦形した材料が上市されている。
天然黒鉛を用いた負極材の出願として、石油ピッチ、石炭ピッチ等の炭素前駆体と天然黒鉛等の黒鉛材とを不活性ガス雰囲気中で１０００〜３０００℃で熱処理する負極材の製造法が提案されている。（例えば、特許文献１参照）。
【００１１】
【特許文献１】
特開平１１−１６７９２０号公報
【００１２】
しかしこれらのいずれも、天然黒鉛の有する急速充放電特性が劣るという欠点までは解決し得ていない。
【００１３】
一方、人造黒鉛では、メソカ−ボンマイクロビ−ズを黒鉛化したもの、バルクメソフェ−ズピッチを粉砕後、黒鉛化したものなどが使用されている。
これら人造黒鉛を用いた負極材は、配向性が小さく、サイクル特性が良好であるが、天然黒鉛に比べ放電容量が低容量で３１０〜３４０ｍＡｈ／ｇ程度にとどまり、現在の顧客ニ−ズには十分なものではない。
【００１４】
人造黒鉛の一つとして高結晶コ−クスにバインダ−ピッチと添加剤を加え、混熱成形し、焼成、黒鉛化、粉砕したものは、３５０〜３６０ｍＡｈ／ｇ程度の容量のものが得られる。
【００１５】
しかし、この方法により得られた負極材は、高容量化は可能だが、電池に使用した場合、生産性、取り扱い性の面で実用化に難がある。
即ち、かかる負極材は、高比表面積、高給油性であり、電極作製時に、用いるバインダ−はＳＢＲ等の水系のものに限られる。
有機系のＰＶＤＦは多量に使用する必要があり、実質的に利用することができない。
【００１６】
ＳＢＲ等の水系バインダ−を用いて調整した塗料は、固形分濃度が低く、塗工困難であったり、仮に塗工できたとしても揮発除去させる水分が多く、生産性が低下する欠点がある。
また塗膜の厚さの調整が難しいため、作製した電極の配向が出てサイクル特性が劣化したり、低嵩密度でハンドリング性に難がある等の問題も生じる。
【００１７】
以上のように、リチウムイオン二次電池用の負極材として、高容量性、容量ロスの低減に加えて、高密度充填性、急速充放電性などの特性を全て十分に満足させ、かつ電池として実用化して問題が生じない優れた材料は未だ開発されていない。
【００１８】
【発明の課題】
上記のような状況に鑑み、本発明者は高容量で、容量ロスが少なくさらに高密度充填性があるリチウムイオン二次電池用負極の製造方法を提供する。
【００１９】
【課題解決の手段】
上記のような課題を解決するために、本発明者が提案するのは、樹脂等のバインダ−を用いて略球状に造粒成形したタップ密度が０．６〜０．９５ｇ/ｃｍ3の黒鉛粉末にバインダ−ピッチを被覆含浸した後、焼成さらに黒鉛化してなるリチウムイオン二次電池用負極材の製造方法。
【００２０】
以下に本発明を詳細に説明する。
【００２１】
まず、出発原料として使用する黒鉛粉末は、鱗片状天然黒鉛粉末、鱗状天然黒鉛粉末、ニ−ドルコ−クスを黒鉛化した人造黒鉛が代表的なものとして挙げられる。
【００２２】
黒鉛粉末の粒径は２〜２０μｍ程度が適当である。
【００２３】
また結晶化度は、炭素結晶面同士の間隔ｄ（002）が０．３３７ｎｍ以下のものを用いる。
これにより、放電容量、電池効率に優れた負極材を得ることができる。
【００２４】
まず、負極材の放電容量は結晶化度と密接な関係があり、結晶化度の上昇に伴い高容量化する。
【００２５】
また電池効率、即ち不可逆容量も、本発明では、黒鉛粉末を略球状に造粒することにより、炭素層面のエッジを粒表面に平行に配向させ、後のピッチ被覆により不可逆容量を低下させているが、この場合も、結晶化度の上昇に伴い、上記の配向が良くなり、エッジ部の被覆がより確実に進行する。
【００２６】
さらに負荷特性については、天然黒鉛等の黒鉛は一般的に良好な負極材が得られないが、この点について、本発明者は、炭素層面の拡がりが大きく、それにより吸蔵されたリチウムの拡散が遅くなることに起因していることを見出した。
そして、この知見に基き、黒鉛粉末とピッチを混合熱処理して、炭素層面にピッチを侵入させることにより、負極材の負荷特性を大幅に改善できる発明を先に出願した。（特願2002-205261）
この場合も炭素層面の明確に発達した、即ち結晶化度が進んだ黒鉛粉末の方がピッチの炭素層面への侵入が容易になる。
【００２７】
このように本発明では、放電容量、電池効率が良好な負極材を得るために、黒鉛粉末は結晶化度ｄ（002）が０．３３７以下に発達したものを用いることが重要である。
【００２８】
天然黒鉛粉末を用いる場合は、灰分が０．２％以下、より好ましくは０．１％以下としたものが望ましいが、後工程の黒鉛化で不純物が気化・除去され、実質的に純化されることになるので、実際用いるものは灰分５％以下程度であれば問題なく、この方が製造コストが安価になる。
【００２９】
上記の黒鉛粉末は、単独で用いるか又は任意の割合で２種類以上混合して用いてもよい。
【００３０】
次に、上記の黒鉛粉末を樹脂等の適当なバインダ−を用いて略球状に造粒する。
造粒に用いるバインダ−は、バインダ−力のある樹脂、ピッチ等であればよく、
特に限定はされない。
【００３１】
バインダ−の例を挙げると、フェノ−ル樹脂、セルロ−ス樹脂、エポキシ樹脂、ポリビニルアルコ−ル、スチレンブタジェンラバ−、ナイロン、ポリエチレン、石油ピッチ、石炭ピッチなどがあり、樹脂とピッチの混合物も用いることができる。
【００３２】
バインダ−の使用量は、種類により多少異なるが、一般には黒鉛粉末１００重量部に対して２〜３０重量部程度が適当である。
バインダ−の使用目的は略球形に賦形することなので、その目的さえ達成できればそれ以上のバインダ−を加える必要はない。
【００３３】
造粒には、一般に市販されている造粒機を用いることができ、機種は特に限定されない。
造粒した黒鉛粉末の球形度は、特に限定されないが、長径と短径の比が２以下程度であれば問題がなく、２を大きく超えるものは、通常の造粒方法では選択的に製造するのは困難である。
【００３４】
造粒された黒鉛粉末等は、バインダ−の種類によっては、その形状を保持するために後処理を施すとよい。
例えば、フェノ−ル樹脂などの熱硬化性樹脂を使用した場合は、１５０℃程度で硬化処理を施すのが適当である。
【００３５】
ここで造粒後の黒鉛粉末のタップ密度は０．６〜０．９５ｇ／ｃｍ3に調整する。
タップ密度が０．９５ｇ／ｃｍ3を超えると、後のピッチの含浸、被覆の工程で、ピッチの炭素層面への侵入が良好に進行せず、負極材の負荷特性が低下する。
また０．６ｇ／ｃｍ3未満では、被覆材であるピッチ由来の黒鉛の量が多くなり、負極材の放電容量が低下する。
【００３６】
本発明では、黒鉛粉末を略球状に造粒することにより、炭素層面のエッジ部が露出する確率を、造粒しない場合や平板状に造粒した場合に比べて大幅に減少させることができる。
また後工程におけるピッチとの混合、加熱による黒鉛粉末への被覆、含浸も物理的により確実に、容易に可能となる。
【００３７】
次に上記のように略球状に造粒した、黒鉛粉末または前駆体をバインダ−ピッチと混合して約８０〜１５０℃で熱処理する。
この混合、熱処理により溶融ピッチを黒鉛粉末内の空隙に含浸させるとともに、表層にも被覆させる。
【００３８】
使用するバインダ−ピッチについては、軟化点が７０〜２００℃（より好ましくは８０〜１５０℃）、メタフェ−ズ量が３〜２５％であるものが好ましい。
【００３９】
軟化点が７０℃未満では後工程の焼成後の造粒物の固着が多くなり、解砕が困難になったり、解砕により被覆ピッチの剥離が発生し、最終的な負極材の電池効率が低下し、また２００℃を超えるとピッチの粘度が高くなり、造粒物への含浸が進行せず、負極材の負荷特性が低下するので好ましくない。
またメタフェ−ズ量が３％未満では、黒鉛化時にピッチの結晶化が進み新たなエッジ生成に起因する急速充電性の劣化が生じ、また２５％を超えると容量が低下する問題がある。
【００４０】
バインダ−ピッチの使用量は黒鉛粉末１００重量部に対して３〜３０重量部であることが好ましい。
【００４１】
３重量部以下では混合した効果がなく、最終品の負極材につき、充放電効率、急速充電性が良好なものが得られない。
また３０重量部を超えると、ピッチの量が過多になり、後工程の焼成において、黒鉛粉末同士を固着させてしまい、焼成後に粉砕が必要になる。
その結果、黒鉛粉末表面の被覆効果がなくなり容量ロスが増加し、さらには結晶化度が低いピッチ由来の炭素材の割合が多くなり過ぎ容量が低下する問題も生じる。
【００４２】
混合に使用する装置は、一般には加熱ニ−ダ−が量産に適しているが、これに限定はされない。
【００４３】
混合、熱処理後は窒素等の非酸化性雰囲気中で７００〜１４００℃、より好ましくは８００〜１１００℃で焼成する。
７００℃未満では、揮発分の除去が不十分になり、１４００℃を超えると量産においてはコスト高となり、いずれも好ましくない。
焼成後の粉砕の必要はなく、解砕処理のみで十分である。
【００４４】
焼成後は、最終熱処理として、非酸化性雰囲気中で２０００〜３２００℃で黒鉛化して本発明の負極材を得る。
黒鉛粉末として天然黒鉛、黒鉛化ニ−ドルコ−クスを単独、又は混合させて用いた場合は、２０００℃以上、より好ましくは２６００℃程度で黒鉛化すればよい。
なお、黒鉛化は３２００℃以上では、処理物の昇華が起こり比表面積を増加させるので好ましくないばかりでなく、実質的に工業的に実施することは、不可能である。
以上のようにして本発明のリチウムイオン二次電池用負極材を得る.。
【００４５】
【発明の効果】
上記のようにして得られた本発明のリチウムイオン二次電池負極材は、高容量であるとともに、初期充放電時の容量ロスが小さい。
また、粒子形状が球形に近いため、電極に用いた場合、配向が等方的かきわめて小さくなるため、良好なサイクル特性を発揮でき、携帯機器を長時間作動させることが可能となる。
本発明の製造方法によるリチウム二次電池負極材は、高性能な材料で、今後も需要が高まると予想される可搬型機器類のパーツ、材料として有用なものである。
【００４６】
【実施例および比較例】
【実施例１】
平均粒径１５μｍ、ｄ（002）が０．３３６ｎｍ、灰分０．１５％とした中国製鱗片状天然黒鉛１００重量部にバインダ−としてダウケミカル社製のエチルセルロ−ス３重量部を用いて造粒成形を行い、平均粒径２３μｍ、タップ密度０．８５ｇ/ｃｍ3の略球形の成形体（長径と短径の比は、１．１〜２．０程度に分布）を調整した。
この成形体１００重量部に対して、軟化点１１０℃、メタフェ−ズ量（ＱＩ量）１３％のコールタ−ルピッチを１５重量部配合して、２軸ニ−ダ−中で、１５０℃に加熱しながら混合した
次にこの混合物を窒素雰囲気中で熱処理し、最高温度１０００℃で６時間保持した後、冷却し、焼成品とした。
焼成品は、粒子同士の強固な融着はなく、（株）セイシン企業製クイックミルで解砕するだけで簡単に解すことができた。
更にこれを黒鉛製の容器に移し替え、タンマン炉にてアルゴン雰囲気中、３０００℃で、黒鉛化して負極材を得た。
【００４７】
次に得られた負極材を用いて以下のように電池を作成し、電池特性を評価した。
本来、黒鉛粉末は負極として用いるが、本発明では対極にリチウム金属を使用したため、正極で電池の特性を評価した。
電極の製造は黒鉛粉末１００重量部とポリフッ化ビニリデン８重量にＮ−メチル−２−ピロリドンを添加してペ−スト化した後、ドクタ−ブレ−ドを用いて銅箔上に塗布し、乾燥させた。
乾燥後、これを１ｃｍ2の面積になるように円形に打ち抜き、更に１ｔｏｎ／ｃｍ2の圧力でプレスし、電極を調整した。
対極及び参照極としてリチウム金属を使用し、電解液として１ＭLiPF6／ＥＣ：ＭＥＣ（体積比１：１）を用いてコインセルを組み立てた。
【００４８】
充電は０．５ｍＡ／ｃｍ2の電流密度で定電流充電後、１０ｍＶで定電圧充電に切り替え、０．０１ｍＡで終止した。
また、放電は、０．５ｍＡ／ｃｍ2の電流密度で定電流放電１．５Ｖまで行った。
更に放電レ−トを変えて５ｍＡ／ｃｍ2の電流密度での放電容量も測定した。
測定温度は３０℃である。
測定結果は放電容量が３６０ｍＡｈ／ｇ、電池効率は９３．２％であった。
また、電流密度が５ｍＡ／ｃｍ2と０．５ｍＡ／ｃｍ2の放電容量の比は、０．９７であった。
【００４９】
【比較例１】
実施例１における鱗状天然黒鉛として、平均粒径が１５μｍ、d(002)が０．３４０ｎｍ、灰分が０．１％の天然黒鉛を用いる以外は、すべて実施例１と同様にして負極材を得た。
得られた負極材を用いて実施例１と同様にして、コインセルを組み、充放電テストを行った結果、放電容量は３４８ｍＡｈ／ｇ、電池効率は８９．５％であった。
また電流密度が５ｍＡ／ｃｍ2と０．５ｍＡ／ｃｍ2の放電容量の比は０．９５であった。
【００５０】
【比較例２】
実施例１における造粒条件を変え、略球形の成形体のタップ密度を１．０５ｇ／ｃｍ3とする以外は、すべて実施例１と同様にして負極材を得た。
得られた負極材で、実施例１と同様にコインセルを組み、充放電テストを行った結果、放電容量は３６２ｍＡｈ／ｇ、電池効率は９２．８％であった。
また、電流密度が５ｍＡ／ｃｍ2と０．５ｍＡ／ｃｍ2の放電容量の比は０．８８であった。
【００５１】
【比較例３】
実施例１におけるコ−ルタ−ルピッチの軟化点を６０℃とし、２軸ニ−ダの加熱温度を１１０℃とする以外は、すべて実施例１と同様に１０００℃で焼成した。 しかしながら、焼成品は固着しており、解砕に長時間を要した。
解砕後、実施例１と同様に黒鉛化して負極材を得た。
得られた負極材を用いて、実施例１と同様にしてコインセルを組み、充放電テストを行った結果、放電容量は３６６ｍＡｈ／ｇ、電池効率は８８．２％であった。
また電流密度が５ｍＡ／ｃｍ2と０．５ｍＡ／ｃｍ2の放電容量の比は０．９６であった。
【００５２】
【比較例４】
実施例１におけるコ−ルタ−ルピッチの軟化点を２５０℃、２軸ニ−ダの加熱温度を３００℃とする以外はすべて実施例１と同様にして負極材を得た。
実施例１と同様にしてコインセルを組み、充放電性を測定した結果、放電容量は３５７ｍＡｈ／ｇ、電池効率が９２．８％であった。
また、電流密度が５ｍＡ／ｃｍ2と ０．５ｍＡ／ｃｍ2の放電容量の比は、０．９１であった。
【００５３】
【比較例５】
実施例１におけるコ−ルタ−ルピッチの添加量を３重量部とする以外は、すべて実施例１と同様にして負極材を得た。
次にこの負極材を用いて実施例１と同様にして電池特性を測定した結果、放電容量は３６７ｍＡｈ／ｇ、電池効率は８７．２％であった。
また電流密度が５ｍＡ／ｃｍ2 ０．５ｍＡ／ｃｍ2の放電容量の比は、０．９０であった。
【００５４】
【実施例２】
熱膨張係数が２．３×１０-6℃の石炭系ニ−ドルコ−クスを黒鉛化した後、粉砕、整粒して平均粒径１６μｍ、d(002)が０．３３６ｎｍで、灰分０．１％の扁平な人造黒鉛粉末を得た。
この粉末１００重量部に対して、バインダ−としてダウケミカル社製のエチルセルロ−ス３重量部を用いて造粒成形を行い、平均粒径２３μｍでタップ密度が０．８０ｇ／ｍ3の略球形成形体（長径と短径の比は、１．１〜２．０程度に分布）を調整した。
この成形体１００重量部に対し、軟化点９５℃、メタフェ−ズ量１１％のコ−ルタ−ルピッチを１５重量部配合して２軸ニ−ダ−中で１５０℃で２時間、加熱混合した。
【００５５】
次いで、この混合物を窒素雰囲気下で熱処理し、最高温度９００℃で６時間保持後、放冷し焼成品を得た。
焼成品は、粒子同士の強固な融着はなく、（株）セイシン企業製クイックミルで解砕するだけで容易に解すことができた。
更にこれを黒鉛製の容器に移し変え、タンマン炉でアルゴン雰囲気下３０００℃で黒鉛化し、負極材を得た。
【００５６】
この負極材を用いて実施例１と同様にコインセルを組み、充放電テストを行った結果、放電容量は３５８ｍＡｈ／ｇ、電池効率は９２．２％であった。
また電流密度が５ｍＡ／ｃｍ2と ０．５ｍＡ／ｃｍ2の放電容量の比は、０．９７であった。
【００５７】
【比較例６】
実施例２におけるコ−ルタ−ルピッチにメタフェ−ズ量が１％以下で、軟化点が９０℃のコ−ルタ−ルピッチを用いる以外はすべて実施例２と同様にして負極材を得た。
次にこの負極材を用いて実施例１と同様にコインセルを組み、充放電テストを行った結果、放電容量は３５５ｍＡｈ／ｇ、電池効率は８９．２％であった。
また電流密度が５ｍＡ／ｃｍ2と ０．５ｍＡ／ｃｍ2の放電容量の比は０．９４であった。[0001]
【Technical field】
The present invention relates to a method for producing a negative electrode material for a lithium ion secondary battery, and more specifically, a high capacity and capacity obtained by coating and impregnating a binder-pitch into a substantially spherical granulated graphite powder, followed by firing and graphitization. The present invention relates to a method for producing a negative electrode material with low loss and high packing density.
[0002]
[Prior art]
In recent years, lithium secondary batteries are often used as high-power, high-capacity secondary batteries in portable devices such as mobile phones and personal computers, and demand is expected to increase further in the future.
[0003]
In response to the trend toward miniaturization of portable devices, there is an increasing demand for lithium secondary batteries to be smaller, lighter, and have higher performance.
[0004]
For this reason, parts and materials constituting lithium secondary batteries are also becoming increasingly active, and among them, the importance of the negative electrode material is increasing as it affects the performance of the battery.
[0005]
Carbon-based materials are attracting attention as this negative electrode material.
Among the characteristics required for carbon-based negative electrode materials, first of all, it is important to have a high discharge capacity and to reduce capacity loss. However, not only these but also a large amount of negative electrode in the battery. A high packing density is required so that the material can be filled, and rapid charge / discharge characteristics are also required.
[0006]
Conventionally, natural graphite and artificial graphite have been used for such a negative electrode material, but no material that satisfies both of the above characteristics has been put on the market.
[0007]
First, natural graphite is an example of a material having a high discharge capacity, and a capacity close to the theoretical value of 372 mAh / g can be obtained.
However, although natural graphite is excellent in terms of capacity increase, there is a drawback due to the fact that the shape is basically flat rather than spherical.
[0008]
That is, the pulverized natural graphite is scaly or scaly and has a large initial discharge capacity, but because of its flat shape, the particles are oriented in parallel with the copper foil of the current collector. The volumetric expansion / contraction of the negative electrode is large, and deterioration of cycle characteristics is an important defect.
In addition, the packing density is not high due to the flat shape.
[0009]
Natural graphite contains as much as 10 to 15% of impurities simply by pulverizing and sizing, and the components and amounts of impurities vary depending on the production area and the ore deposit.
For this reason, when used in battery applications, considering the efficiency of discharge capacity and safety issues with respect to the amount of natural graphite used, it is necessary to apply a deashing treatment to reduce the impurities to 0.2% or less. Manufacturing costs increase.
In addition, there is earthy graphite as a kind of natural graphite, but it is not preferable because only a low-capacity negative electrode material can be obtained compared to scaly and scaly natural graphite because of poor crystal development.
[0010]
Thus, attempts have been made to eliminate the drawbacks while taking advantage of the excellent discharge capacity of natural graphite.
A material obtained by pulverizing natural graphite lumps so as to be substantially spherical by a special method, or a material obtained by shaping flaky or scaly natural graphite powder into a substantially spherical shape by using an appropriate binder has been put on the market.
As an application for a negative electrode material using natural graphite, a method for producing a negative electrode material is proposed in which a carbon precursor such as petroleum pitch or coal pitch and a graphite material such as natural graphite are heat-treated at 1000 to 3000 ° C. in an inert gas atmosphere. Has been. (For example, refer to Patent Document 1).
[0011]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-167920
However, none of these have been able to solve the disadvantage that the natural charge and discharge characteristics of natural graphite are inferior.
[0013]
On the other hand, for artificial graphite, those obtained by graphitizing mesocarbon micro beads, those obtained by pulverizing bulk mesophase pitch and then graphitizing are used.
These negative electrode materials using artificial graphite have small orientation and good cycle characteristics, but the discharge capacity is only about 310 to 340 mAh / g at a low capacity compared to natural graphite. Not enough.
[0014]
As one of artificial graphite, a binder having a binder pitch and an additive added to high-crystal coke, mixed heat-molded, fired, graphitized, and pulverized can have a capacity of about 350 to 360 mAh / g.
[0015]
However, the negative electrode material obtained by this method can be increased in capacity, but when used in a battery, it is difficult to put it into practical use in terms of productivity and handleability.
That is, such a negative electrode material has a high specific surface area and a high oil supply property, and a binder used for producing an electrode is limited to a water-based material such as SBR.
Organic PVDF needs to be used in a large amount and cannot be practically used.
[0016]
A paint prepared using an aqueous binder such as SBR has a low solid content and is difficult to apply. Even if it can be applied, there is a large amount of water to be volatilized and removed, resulting in reduced productivity.
Further, since it is difficult to adjust the thickness of the coating film, problems such as the orientation of the produced electrode appearing and the cycle characteristics are deteriorated, or the handling property is difficult due to the low bulk density.
[0017]
As described above, as a negative electrode material for a lithium ion secondary battery, in addition to high capacity and reduction in capacity loss, it fully satisfies all characteristics such as high density filling and rapid charge and discharge, and as a battery. An excellent material that does not cause any problems after practical use has not yet been developed.
[0018]
[Problems of the Invention]
In view of the above situation, the present inventor provides a method for producing a negative electrode for a lithium ion secondary battery that has a high capacity, a small capacity loss, and a high density filling property.
[0019]
[Means for solving problems]
In order to solve the above problems, the present inventor proposes a graphite having a tap density of 0.6 to 0.95 g / cm 3 which is granulated and formed into a substantially spherical shape using a binder such as a resin. A method for producing a negative electrode material for a lithium ion secondary battery, which is obtained by coating and impregnating powder with a binder pitch, followed by firing and graphitization.
[0020]
The present invention is described in detail below.
[0021]
First, typical graphite powder used as a starting material includes scaly natural graphite powder, scaly natural graphite powder, and artificial graphite obtained by graphitizing needle coke.
[0022]
The particle size of the graphite powder is suitably about 2 to 20 μm.
[0023]
The crystallinity is such that the distance d (002) between the carbon crystal planes is 0.337 nm or less.
Thereby, the negative electrode material excellent in discharge capacity and battery efficiency can be obtained.
[0024]
First, the discharge capacity of the negative electrode material is closely related to the degree of crystallinity, and the capacity increases as the degree of crystallinity increases.
[0025]
In addition, in the present invention, the battery efficiency, that is, the irreversible capacity is also reduced by pulverizing the graphite powder into a substantially spherical shape so that the edge of the carbon layer surface is oriented parallel to the grain surface, and the irreversible capacity is reduced by subsequent pitch coating. However, also in this case, as the degree of crystallinity increases, the above-mentioned orientation is improved, and the covering of the edge portion proceeds more reliably.
[0026]
Further, regarding the load characteristics, graphite such as natural graphite generally does not provide a good negative electrode material, but in this respect, the present inventors have a large carbon layer surface, which causes the diffusion of the occluded lithium. I found out that it was due to slowness.
Based on this knowledge, the inventors filed an invention that can greatly improve the load characteristics of the negative electrode material by mixing and heat-treating graphite powder and pitch and allowing the pitch to penetrate into the carbon layer surface. (Japanese Patent Application 2002-205261)
Also in this case, the graphite powder having a clearly developed carbon layer surface, that is, a graphite powder having a higher degree of crystallinity, can easily penetrate the pitch into the carbon layer surface.
[0027]
As described above, in the present invention, in order to obtain a negative electrode material having good discharge capacity and battery efficiency, it is important to use graphite powder having a crystallinity d (002) of 0.337 or less.
[0028]
When natural graphite powder is used, it is desirable that the ash content is 0.2% or less, more preferably 0.1% or less. However, impurities are vaporized and removed by subsequent graphitization, and are substantially purified. Therefore, there is no problem if the actually used one has an ash content of about 5% or less, and this makes the production cost cheaper.
[0029]
The above graphite powders may be used alone or in combination of two or more at any ratio.
[0030]
Next, the graphite powder is granulated into a substantially spherical shape using a suitable binder such as a resin.
The binder used for granulation may be a resin having a binder force, a pitch, etc.
There is no particular limitation.
[0031]
Examples of binders include phenolic resin, cellulose resin, epoxy resin, polyvinyl alcohol, styrene butadiene rubber, nylon, polyethylene, petroleum pitch, coal pitch, etc., and a mixture of resin and pitch. Can also be used.
[0032]
The amount of binder used is somewhat different depending on the type, but generally about 2 to 30 parts by weight is appropriate for 100 parts by weight of graphite powder.
Since the purpose of use of the binder is to form a substantially spherical shape, it is not necessary to add more binder if the purpose can be achieved.
[0033]
For granulation, a commercially available granulator can be used, and the model is not particularly limited.
The sphericity of the granulated graphite powder is not particularly limited, but there is no problem as long as the ratio of the major axis to the minor axis is about 2 or less, and those that greatly exceed 2 are selectively produced by a normal granulation method. It is difficult.
[0034]
Depending on the type of the binder, the granulated graphite powder or the like may be post-treated to maintain its shape.
For example, when a thermosetting resin such as phenol resin is used, it is appropriate to perform the curing process at about 150 ° C.
[0035]
Here, the tap density of the graphite powder after granulation is adjusted to 0.6 to 0.95 g / cm 3 .
When the tap density exceeds 0.95 g / cm 3 , the penetration of the pitch into the carbon layer surface does not proceed well in the subsequent pitch impregnation and coating process, and the load characteristics of the negative electrode material are deteriorated.
On the other hand, if it is less than 0.6 g / cm 3 , the amount of pitch-derived graphite that is a coating material increases, and the discharge capacity of the negative electrode material decreases.
[0036]
In the present invention, by granulating the graphite powder into a substantially spherical shape, the probability that the edge portion of the carbon layer surface is exposed can be greatly reduced as compared with the case where it is not granulated or when it is granulated into a flat plate shape.
Further, mixing with pitch, coating with graphite powder by heating, and impregnation in the subsequent process can be physically and reliably performed easily.
[0037]
Next, the graphite powder or precursor granulated into a substantially spherical shape as described above is mixed with a binder pitch and heat-treated at about 80 to 150 ° C.
This mixing and heat treatment impregnate the molten pitch with voids in the graphite powder and also coat the surface layer.
[0038]
The binder pitch used is preferably one having a softening point of 70 to 200 ° C. (more preferably 80 to 150 ° C.) and a metaphase amount of 3 to 25%.
[0039]
If the softening point is less than 70 ° C., the fixed granulated product after firing in the subsequent process increases, and it becomes difficult to crush or the coating pitch is peeled off by crushing, so that the battery efficiency of the final negative electrode material is improved. If the temperature is lower than 200 ° C., the viscosity of the pitch is increased, the impregnation into the granulated product does not proceed, and the load characteristics of the negative electrode material are deteriorated.
If the metaphase amount is less than 3%, the crystallization of pitch proceeds during graphitization, resulting in deterioration of rapid chargeability due to generation of a new edge, and if it exceeds 25%, the capacity decreases.
[0040]
The amount of the binder pitch used is preferably 3 to 30 parts by weight with respect to 100 parts by weight of the graphite powder.
[0041]
When the amount is 3 parts by weight or less, there is no mixed effect, and the final negative electrode material cannot be obtained with good charge / discharge efficiency and rapid chargeability.
On the other hand, if the amount exceeds 30 parts by weight, the amount of the pitch becomes excessive, and the graphite powders are fixed to each other in the subsequent firing, and pulverization is required after firing.
As a result, the covering effect on the surface of the graphite powder is lost, the capacity loss is increased, and furthermore, the proportion of the carbon material derived from pitch having a low crystallinity is increased so that the capacity is lowered.
[0042]
The apparatus used for mixing is generally a heat kneader suitable for mass production, but is not limited thereto.
[0043]
After mixing and heat treatment, firing is performed at 700 to 1400 ° C., more preferably at 800 to 1100 ° C. in a non-oxidizing atmosphere such as nitrogen.
If it is less than 700 degreeC, removal of a volatile matter will become inadequate, and if it exceeds 1400 degreeC, it will become expensive in mass production, and neither is preferable.
There is no need for pulverization after firing, and only pulverization is sufficient.
[0044]
After firing, as a final heat treatment, it is graphitized at 2000 to 3200 ° C. in a non-oxidizing atmosphere to obtain the negative electrode material of the present invention.
When natural graphite or graphitized needle coke is used alone or mixed as the graphite powder, it may be graphitized at 2000 ° C. or higher, more preferably at about 2600 ° C.
It should be noted that graphitization is not preferable at 3200 ° C. or higher because it causes sublimation of the treated product and increases the specific surface area, and it is impossible to implement it practically industrially.
As described above, a negative electrode material for a lithium ion secondary battery of the present invention is obtained.
[0045]
【The invention's effect】
The lithium ion secondary battery negative electrode material of the present invention obtained as described above has a high capacity and a small capacity loss during initial charge / discharge.
In addition, since the particle shape is close to a sphere, when used for an electrode, the orientation is isotropic or extremely small, so that good cycle characteristics can be exhibited and the portable device can be operated for a long time.
The negative electrode material for a lithium secondary battery according to the production method of the present invention is a high-performance material, and is useful as a part or material for portable equipment, for which demand is expected to increase in the future.
[0046]
Examples and Comparative Examples
[Example 1]
Granulation using 100 parts by weight of Chinese scale-like natural graphite having an average particle size of 15 μm, d (002) of 0.336 nm, and ash content of 0.15%, using 3 parts by weight of ethyl cellulose manufactured by Dow Chemical as a binder. Molding was performed to adjust a substantially spherical shaped body (the ratio of the major axis to the minor axis distributed about 1.1 to 2.0) having an average particle size of 23 μm and a tap density of 0.85 g / cm 3 .
15 parts by weight of a coal tar pitch with a softening point of 110 ° C. and a metaphase amount (QI amount) of 13% is blended with 100 parts by weight of this molded body and heated to 150 ° C. in a biaxial kneader. Next, the mixture was heat-treated in a nitrogen atmosphere, held at a maximum temperature of 1000 ° C. for 6 hours, and then cooled to obtain a fired product.
The fired product did not have a strong fusion between the particles, and could be easily broken simply by crushing with a quick mill manufactured by Seishin Corporation.
Further, this was transferred to a graphite container and graphitized in a Tamman furnace at 3000 ° C. in an argon atmosphere to obtain a negative electrode material.
[0047]
Next, a battery was prepared as follows using the obtained negative electrode material, and the battery characteristics were evaluated.
Originally, graphite powder is used as a negative electrode, but in the present invention, lithium metal was used for the counter electrode, and thus the characteristics of the battery were evaluated using the positive electrode.
The electrode was manufactured by adding N-methyl-2-pyrrolidone to 100 parts by weight of graphite powder and 8 parts of polyvinylidene fluoride to form a paste, and then applying the paste onto a copper foil using a doctor blade and drying. I let you.
After drying, this was punched out in a circular shape so as to have an area of 1 cm 2 , and further pressed with a pressure of 1 ton / cm 2 to adjust the electrode.
A coin cell was assembled using lithium metal as a counter electrode and a reference electrode, and using 1M LiPF6 / EC: MEC (volume ratio 1: 1) as an electrolyte.
[0048]
Charging was performed at a current density of 0.5 mA / cm 2 and then switched to constant voltage charging at 10 mV and terminated at 0.01 mA.
The discharge was performed at a current density of 0.5 mA / cm 2 up to a constant current discharge of 1.5V.
Further, the discharge capacity at a current density of 5 mA / cm 2 was measured by changing the discharge rate.
The measurement temperature is 30 ° C.
The measurement results were a discharge capacity of 360 mAh / g and a battery efficiency of 93.2%.
The ratio of the discharge capacities at a current density of 5 mA / cm 2 and 0.5 mA / cm 2 was 0.97.
[0049]
[Comparative Example 1]
A negative electrode material was obtained in the same manner as in Example 1 except that natural graphite having an average particle diameter of 15 μm, d (002) of 0.340 nm, and ash content of 0.1% was used as the scale-like natural graphite in Example 1. It was.
As a result of assembling a coin cell and performing a charge / discharge test in the same manner as in Example 1 using the obtained negative electrode material, the discharge capacity was 348 mAh / g, and the battery efficiency was 89.5%.
The ratio of discharge capacities at a current density of 5 mA / cm 2 and 0.5 mA / cm 2 was 0.95.
[0050]
[Comparative Example 2]
A negative electrode material was obtained in the same manner as in Example 1 except that the granulation conditions in Example 1 were changed and the tap density of the substantially spherical shaped product was 1.05 g / cm 3 .
As a result of assembling a coin cell in the same manner as in Example 1 and conducting a charge / discharge test with the obtained negative electrode material, the discharge capacity was 362 mAh / g, and the battery efficiency was 92.8%.
The ratio of discharge capacities at a current density of 5 mA / cm 2 and 0.5 mA / cm 2 was 0.88.
[0051]
[Comparative Example 3]
All were fired at 1000 ° C. in the same manner as in Example 1 except that the softening point of the cold tar pitch in Example 1 was 60 ° C. and the heating temperature of the biaxial kneader was 110 ° C. However, the fired product was fixed and required a long time for crushing.
After crushing, it was graphitized in the same manner as in Example 1 to obtain a negative electrode material.
Using the obtained negative electrode material, a coin cell was assembled in the same manner as in Example 1 and a charge / discharge test was performed. As a result, the discharge capacity was 366 mAh / g, and the battery efficiency was 88.2%.
The ratio of the discharge capacities at a current density of 5 mA / cm 2 and 0.5 mA / cm 2 was 0.96.
[0052]
[Comparative Example 4]
A negative electrode material was obtained in the same manner as in Example 1 except that the softening point of the cold tar pitch in Example 1 was 250 ° C. and the heating temperature of the biaxial kneader was 300 ° C.
As a result of assembling coin cells and measuring charge / discharge performance in the same manner as in Example 1, the discharge capacity was 357 mAh / g, and the battery efficiency was 92.8%.
The ratio of the discharge capacities at a current density of 5 mA / cm 2 and 0.5 mA / cm 2 was 0.91.
[0053]
[Comparative Example 5]
A negative electrode material was obtained in the same manner as in Example 1 except that the amount of addition of the coal tar pitch in Example 1 was 3 parts by weight.
Next, using this negative electrode material, the battery characteristics were measured in the same manner as in Example 1. As a result, the discharge capacity was 367 mAh / g, and the battery efficiency was 87.2%.
The ratio of the discharge capacity at a current density of 5 mA / cm 2 and 0.5 mA / cm 2 was 0.90.
[0054]
[Example 2]
After graphitizing a coal-based nickel coke having a thermal expansion coefficient of 2.3 × 10 −6 ° C., it was pulverized and sized to have an average particle size of 16 μm, d (002) of 0.336 nm, and an ash content of 0. 1% flat artificial graphite powder was obtained.
For 100 parts by weight of this powder, granulation molding is carried out using 3 parts by weight of ethyl cellulose manufactured by Dow Chemical Co. as a binder to form a substantially sphere with an average particle diameter of 23 μm and a tap density of 0.80 g / m 3. The shape (the ratio of the major axis to the minor axis was distributed to about 1.1 to 2.0) was adjusted.
To 100 parts by weight of this molded body, 15 parts by weight of a coal tar pitch with a softening point of 95 ° C. and a metaphase amount of 11% was blended and heated and mixed at 150 ° C. for 2 hours in a biaxial kneader. .
[0055]
Next, this mixture was heat-treated in a nitrogen atmosphere, held at a maximum temperature of 900 ° C. for 6 hours, and then allowed to cool to obtain a fired product.
The fired product did not have a strong fusion between the particles, and could be easily broken by simply crushing it with a quick mill manufactured by Seishin Corporation.
Further, this was transferred to a graphite vessel and graphitized in a Tamman furnace at 3000 ° C. in an argon atmosphere to obtain a negative electrode material.
[0056]
Using this negative electrode material, a coin cell was assembled in the same manner as in Example 1, and a charge / discharge test was performed. As a result, the discharge capacity was 358 mAh / g, and the battery efficiency was 92.2%.
The ratio of the discharge capacities at a current density of 5 mA / cm 2 and 0.5 mA / cm 2 was 0.97.
[0057]
[Comparative Example 6]
A negative electrode material was obtained in the same manner as in Example 2, except that a coal tar pitch in Example 2 was 1% or less and a soft pitch of 90 ° C. was used.
Next, a coin cell was assembled using this negative electrode material in the same manner as in Example 1, and a charge / discharge test was performed. As a result, the discharge capacity was 355 mAh / g, and the battery efficiency was 89.2%.
The ratio of discharge capacities at a current density of 5 mA / cm 2 and 0.5 mA / cm 2 was 0.94.
Claims (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002344805A JP3716830B2 (en) | 2002-11-28 | 2002-11-28 | Method for producing negative electrode material for lithium ion secondary battery |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002344805A JP3716830B2 (en) | 2002-11-28 | 2002-11-28 | Method for producing negative electrode material for lithium ion secondary battery |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2004179015A JP2004179015A (en) | 2004-06-24 |
| JP3716830B2 true JP3716830B2 (en) | 2005-11-16 |
Family
ID=32706149
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2002344805A Expired - Fee Related JP3716830B2 (en) | 2002-11-28 | 2002-11-28 | Method for producing negative electrode material for lithium ion secondary battery |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3716830B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007141905A1 (en) | 2006-06-02 | 2007-12-13 | Nippon Carbon Co., Ltd. | Negative electrode active material for lithium ion rechargeable battery, and negative electrode |
| WO2008010312A1 (en) | 2006-07-19 | 2008-01-24 | Nippon Carbon Co., Ltd. | Negative electrode active material and negative electrode for lithium ion rechargeable battery |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4215633B2 (en) * | 2002-12-19 | 2009-01-28 | Ｊｆｅケミカル株式会社 | Method for producing composite graphite particles |
| EP1683219B1 (en) * | 2003-10-31 | 2015-12-23 | Showa Denko K.K. | Carbon material for battery electrode and production method and use thereof |
| JP2007242282A (en) * | 2006-03-06 | 2007-09-20 | Sony Corp | Battery |
| JP2009266816A (en) * | 2008-04-21 | 2009-11-12 | Ls Mtron Ltd | Negative electrode active material for secondary battery, electrode for secondary battery containing the same, secondary battery and method of manufacturing them |
| KR101384216B1 (en) * | 2009-03-02 | 2014-04-14 | (주)포스코켐텍 | Composite graphite particles and lithium secondary battery using the same |
| CN104037417B (en) * | 2013-03-04 | 2017-12-01 | 上海杉杉科技有限公司 | A kind of modified natural graphite and preparation method thereof |
| CN105024074B (en) * | 2014-04-18 | 2017-11-07 | 天津尚能巨源能源科技有限公司 | A kind of preparation method using resin as the lithium ion battery negative material of raw material |
| CN115571876A (en) * | 2014-07-07 | 2023-01-06 | 三菱化学株式会社 | Carbon material, method for producing carbon material, and nonaqueous secondary battery using carbon material |
| EP4018495A4 (en) * | 2019-08-21 | 2023-10-04 | Syrah Resources Limited | Lithium-ion battery anode material based on spherical natural graphite containing silicates |
| CN112670461B (en) * | 2019-12-31 | 2022-11-29 | 宁波杉杉新材料科技有限公司 | Natural graphite carbon coated negative electrode material, preparation method thereof and lithium ion battery |
| US20230147558A1 (en) * | 2021-11-09 | 2023-05-11 | Microvast Power Systems Co., Ltd. | Negative electrode material and method of preparing the same |
| KR102691511B1 (en) * | 2022-05-20 | 2024-08-05 | 주식회사 엘피엔 | Novel manufacturing method of conglomerated graphite, conglomerated graphite manufactured using the same, and secondary battery comprising the same as an anode active material |
-
2002
- 2002-11-28 JP JP2002344805A patent/JP3716830B2/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007141905A1 (en) | 2006-06-02 | 2007-12-13 | Nippon Carbon Co., Ltd. | Negative electrode active material for lithium ion rechargeable battery, and negative electrode |
| WO2008010312A1 (en) | 2006-07-19 | 2008-01-24 | Nippon Carbon Co., Ltd. | Negative electrode active material and negative electrode for lithium ion rechargeable battery |
| US10283775B2 (en) | 2006-07-19 | 2019-05-07 | Nippon Carbon Co., Ltd. | Negative electrode active material for lithum ion rechargeable battery and negative electrode using the same |
| US11276858B2 (en) | 2006-07-19 | 2022-03-15 | Nippon Carbon Co., Ltd. | Negative electrode active material for lithium ion rechargeable battery and negative electrode using the same |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2004179015A (en) | 2004-06-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4252846B2 (en) | Lithium secondary battery | |
| CN107078288B (en) | Graphite particle for negative electrode material of lithium ion secondary battery, negative electrode of lithium ion secondary battery, and lithium ion secondary battery | |
| KR100567113B1 (en) | Lithium secondary battery | |
| EP2208247B1 (en) | Core-shell type anode active material for lithium secondary battery, method for preparing the same and lithium secondary battery comprising the same | |
| WO2016169149A1 (en) | Recycling method for graphite fine powder to act as lithium ion battery negative electrode material | |
| KR102699307B1 (en) | Positive electrode additive and its manufacturing method, positive electrode and its manufacturing method and lithium ion battery | |
| JP3716818B2 (en) | Method for producing negative electrode material for high performance lithium ion secondary battery using natural graphite | |
| JP6193798B2 (en) | Method for producing negative electrode material for lithium ion secondary battery | |
| EP2602851A1 (en) | Anode active material for lithium secondary battery | |
| JP3716830B2 (en) | Method for producing negative electrode material for lithium ion secondary battery | |
| KR20130094853A (en) | Anode material for lithium ion rechargeable battery, anode for lithium ion rechargeable battery, and lithium ion rechargeable battery | |
| JP5128063B2 (en) | Composite graphite and lithium secondary battery using the same | |
| CN113226986A (en) | Method for preparing negative active material of lithium secondary battery | |
| CN108172791B (en) | Composite negative electrode material, preparation method thereof and lithium ion battery | |
| KR20160118274A (en) | Negative electrode material for lithium ion secondary battery, negative electrode, and lithium ion secondary battery | |
| WO2017024897A1 (en) | Preparation method for modified lithium-ion battery negative electrode material | |
| WO2016169150A1 (en) | Method for graphite fine powder to be doped and used as negative electrode material | |
| JP2019175851A (en) | Negative electrode active material for lithium ion secondary batteries and manufacturing method therefor | |
| JP2003173774A (en) | Anode material for lithium ion secondary battery and its manufacturing method and lithium ion secondary battery using same anode material | |
| JP2011060467A (en) | Negative electrode material for lithium ion secondary battery and method for manufacturing the same | |
| JP2007173156A (en) | Negative electrode material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, and lithium ion secondary battery | |
| JPH10294111A (en) | Graphite carbon material coated with graphite for lithium secondary battery negative electrode material and its manufacture | |
| CN108565461B (en) | Battery cathode material, preparation method thereof and battery cathode prepared from material | |
| JP2011258421A (en) | Negative electrode active material for lithium ion secondary battery and negative electrode | |
| CN114156446B (en) | Negative electrode active material, negative electrode plate containing same and lithium ion battery |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20050124 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20050208 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20050323 |
|
| 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: 20050809 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20050822 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 3716830 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: 20090909 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090909 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100909 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100909 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110909 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120909 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120909 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130909 Year of fee payment: 8 |
|
| 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 |
|
| LAPS | Cancellation because of no payment of annual fees |