JP3712288B2 - Nonaqueous solvent secondary battery electrode material and method for producing the same - Google Patents

Description

本願発明において、かかる残炭率が少なすぎると、黒鉛性炭素質物の細孔への有機物の充填が不十分となると考えられ、ａ．多相構造炭素質物の表面に黒鉛が露出しやすくなるため、電解液との安定性が低下する、ｂ．細孔内に残ったガスが熱処理過程で噴出することにより、多相構造が破壊される恐れがある、ｃ．細孔が残ったままだと、導電性の悪化や金属イオン移動の妨げの原因になったり、又は、活物質である複合炭素質物の電解液に対する濡れ性が低いために、金属イオンの吸蔵・放出が行われる炭素質物表面が金属イオンの授受に関して均一に利用されない等の問題が生じる。一方、残炭量が大きすぎる場合には、黒鉛性炭素質物の表面の細孔へ有機物が充填される以上の有機物により、複合炭素質物の物性が変化し悪影響が生ずるものと考えられるが、放電容量が低下し、充放電効率が低下し、理論状電極容量の最大である黒鉛性炭素質物の特性を有効に利用することができなくなる。
【００１４】
尚、本発明の製造方法では、黒鉛性炭素質物（Ｎ）を有機物中、好ましくは５０℃における粘度が２００ｃｐ以下の有機物中に混合し、分散し、有機物と接触させることで、有機物、特に重質油中に含まれる多環芳香族分子、好ましくはより分子量の大きな多環芳香族オリゴマーによって黒鉛性炭素質粒子の表面及び細孔内を置換する操作を行う。しかし、５０℃における粘度が２００ｃｐを超える重質油を用いる場合は、有機物の均一で効率的な黒鉛性炭素質物への吸着含浸を行うために、溶媒、例えばトルエン、キシレン、アルキルベンゼン等の芳香族系有機溶媒やキノリンやピリジン等の複素環式化合物からなる溶媒を黒鉛性炭素質物（Ｎ）と有機物との混合体に添加することが好ましい。尚、芳香族系有機溶媒の方が本発明には好ましい。
【００１５】
更に、本発明では、黒鉛性炭素質物（Ｎ）を予め溶媒処理しておくことも有用である。炭素質物粒子（Ｎ）を、芳香族系溶媒に浸漬し、表面及び細孔中を溶媒により置換しておき、しかる後に過剰な溶媒から分離しておいた炭素質物粒子を用いることで、炭素質物粒子（Ｎ）の有機物に対する「ぬれ」をよくする効果が得られる。有機溶媒の添加割合としては、黒鉛性炭素質物と有機物との混合体に溶媒を加えた状態がスラリー状になるまで添加することが望ましい。好ましくは５０℃でのスラリー粘度にして、１００００ｃｐ以下、更に好ましくは、５０００ｃｐ以下、なお更に好ましくは１０００ｃｐ以下である。有機物が固体である場合は溶媒により溶解し、液体であるものの場合は希釈により粘度調整を行う必要がある。なお、有機物を溶解する際に、重質油の全成分が必ずしも全て溶解する必要はなく、所定の粘度範囲で液状化していれば良い。重質油の粘度が１０Ｐａｓ（１００００ｃＰ）を越えると、電極性能にばらつきが生じる為、好ましくない。これは有機物が炭素質物（Ｎ）に存在する細孔へ充填されにくくなるからと考えられる。
【００１６】
この充填が不十分だと、上記のａ、ｂ及びｃ等の問題が生じ易くなる。
（３）製造方法
一方、本願発明のかかる複合炭素質物を得るための、本願発明の製造方法について以下に説明する。
本願発明の複合炭素質物の製造方法は主に次の工程からなる。
（Ａ）炭素質物（Ｎ）と有機物、及び好ましくは溶媒とを混合し、混合物を得る工程。
（Ｂ）前記混合物を攪拌しながら加熱し、中間物質を得る工程。
（Ｃ）前記中間物質を、不活性ガス雰囲気下で６００℃以上好ましくは２５００℃以下に加熱し、炭素化物質を得る工程。
（Ｄ）前記炭素化物質を粉体加工する工程。
Ａ．混合工程
本発明における第１工程では、炭素質物（Ｎ）と有機物、及び好ましくは前述の溶媒を添加混合する。混合工程は回分式または連続式のいずれの装置で行っても良い。また、室温で行っても良いし、反応槽を加温して行っても良い。反応槽を加温することで混合物の粘度を低下させ、装置にかかる負荷を低減し、混合効率を高めることが出来る。更に混合時の槽内圧力を減圧状態にすることで、微小粉末からの脱泡効果を高め、分散性の向上を図ることも可能である。
【００１７】
回分式の場合、混合装置は撹拌翼を備えた混合機１機で構成しても、複数台で構成して順次、分散度の向上を図っても良い。回分式混合装置としては、２本の枠型ブレードが固定式タンク内で遊星運動を行いながら回転する構造を有する混合機、高速高剪断ミキサーであるディゾルバーや高粘度用のバタフライミキサーの様な一枚のブレードがタンク内を撹拌・分散を行う形態の装置、半円筒状混合槽の側面に沿ってシグマ型等の撹拌翼が回転する構造を有する、いわゆるニーダー形式の装置、撹拌翼を合計３軸にしたトリミックスタイプの装置、分散槽内に回転ディスクと分散媒体を有するいわゆるビーズミル形式の装置等を用いることができる。いずれの装置を用いるかは、炭素質物（Ｎ）と有機物とを混合した際の粘度を考慮して決定すればよい。
【００１８】
一方、連続式の装置を用いる場合には、パイプラインミキサーを用いても良いし、連続式ビーズミル（媒体分散機）を用いても良い。更に通常の樹脂加工等に用いられる混練機に液漏れ対策を施して用いても良い。混合装置と次工程を受け持つ装置が別個の場合は、連続式混合機を用いることにより、次工程を受け持つ装置への搬送を混合と同時に行うことができ、製造工程をより効率化することができる。
【００１９】
また、内部に一本のシャフトとシャフトに固定された複数のすき状又は鋸歯状のパドルがパドルが位相を変えて複数配置された反応室を有し、その内壁面は、パドルの回転の最外線に沿った円筒型に形成され、その隙間を最小限とし、パドルはシャフトの軸方向に複数枚配列された構造の外熱式反応装置を用いれば、同一装置で混合工程と中間物質を得る工程とを行なうことができる。
Ｂ．中間物質を得る工程（脱揮・重縮合反応工程）
混合工程で炭素質物（Ｎ）が十分均一に分散し、また炭素質物（Ｎ）の細孔にも有機物が十分充填された混合物は、本工程で混練（攪拌）されながら加熱され、炭素質物粒子（Ｎ）と有機物成分が高度に分散し、かつ有機物に一定の揮発分の除去と加熱処理が行われた中間生成物として回収される。
【００２０】
本工程においては、常に攪拌しながら加熱することがもっとも重要な点である。本工程に適した装置としては、（ａ）図１に示すような、内部にシャフト(1)によって回転されるパドル(2)が内装された反応室(3)を有し、反応室内壁面はパドルの回転の最外線に実質的に沿って、好ましくは長い双胴型に形成され、パドルは互いに対向する側面を摺動可能に咬合するようにシャフトの軸方向に多数対配列された構造を有する反応機、（ｂ）図２に示すような、内部に一本のシャフト(11)とシャフトに固定された複数のすき状又は鋸歯状のパドル(12)がパドルが位相を変えて複数配置された反応室(13)を有し、その内壁面は、パドルの回転の最外線に実質的に沿って、好ましくは円筒型に形成された、その隙間を最小限とし、パドルはシャフトの軸方向に複数枚配列された構造の（外熱式）反応装置を挙げることができる。この様な構造を有する反応装置を用いることにより、炭素質物粒子（Ｎ）の細孔部分にも炭素質物（Ｓ）が充填された、品質の良好な非水溶媒二次電池負極材料を得ることができる。
【００２１】
上述の（ａ）タイプの反応装置としては例えば栗本鉄工所（株）製の「ＫＲＣリアクタ」や「ＳＣプロセッサ」、（株）東芝機械セルマック製の「ＴＥＭ」、（株）日本製鋼所製の「ＴＥＸ−Ｋ」がある。また、（ｂ）タイプの反応装置としては例えばレーディゲ社製の「レディゲミキサー」、太平洋機工社製の「プローシェアーミキサー」、月島機械（株）製の「ＤＴドライヤー」がある。
【００２２】
さらに上述の（ｂ）タイプの装置において、反応室内壁面に高速で回転するスクリュー型解砕翼（１４）を一段或いは多段に一個或いは複数個設置することは、混合操作、或いはその後の反応操作において凝集体の発生を防ぐことをより確実とし、より均一な中間物質を得られるため、好ましい。
この様な反応装置を用いることにより、
イ）本願発明の電極材料の様な、極薄い有機物を均一、かつ効率的に黒鉛性炭素質物の表面に付着することができること。
ロ）炭素材料の製造には必要不可欠である、有機物が十分に芳香族化した構造に変化するまでの熱処理工程を連続的に行うことができること。
ハ）有機物の反応槽内壁への固着を、撹半翼により抑制することができる。
ニ）解砕翼の回転が遠心渦流を発生し、原料の精密な混合が可能な上、だまの発生を防ぐ。これにより、混合工程においては炭素質物粒子と有機物とが非常によく分散され、反応工程においては反応物が流動性を示さなくなった後も撹半が可能となり、炭素質物粒子が均一に分散し、細孔内まで被覆炭素が充填され、かつ反応槽内での場所による偏りの無い、均一に加熱処理された製品を得ることができる。
ホ）特に（ｂ）タイプの反応装置を用いた場合は混合工程と中間物質を得る工程を同時に行うことができる。
等の利点がある。
【００２３】
本工程において、反応装置内の雰囲気は不活性雰囲気又は非酸化性雰囲気が望ましいが、中間物質が酸化による劣化を伴わない条件であれば特に雰囲気を限定しなくても良い。更に反応槽内圧力を減圧状態にすることで、微小粉末からの脱泡効果を高め、分散性の向上を図り、黒鉛性炭素質物・有機物混合スラリーからの揮発分除去効果を高めることもできる。本工程における熱処理温度は、有機物の種類により最適条件が異なるが、溶媒の沸点以上、通常５０℃〜６００℃の範囲で、好ましくは５０℃〜５００℃の範囲である。
Ｃ．炭素化物質を得る工程（炭素化工程）
脱揮・重縮合工程より得られた炭素質物粒子（Ｎ）と十分に芳香族化した（炭素前駆体化した）有機物からなる中間物質は本工程において窒素ガス、炭酸ガス、アルゴンガス等不活性ガス流通下で加熱される。本工程においては炭素前駆体の熱化学反応が進行し、前駆体の組成中に残留した酸素、窒素、水素が系外へ排出されるとともに、構造欠陥が加熱処理の度合いによって除去され、黒鉛化の度合いを高めていく。
【００２４】
本工程の加熱処理条件としては、熱履歴温度条件が重要である。その温度下限は芳香族化した重質油の種類、その熱履歴によっても若干異なるが通常６００℃以上、好ましくは８００℃以上、更に好ましくは８５０℃以上である。一方、上限温度は基本的に炭素質物（Ｎ）の結晶構造を上回る構造秩序を有しない温度まで上げることができる。従って熱処理の上限温度としては、通常２５００℃以下、好ましくは２０００℃以下、更に好ましくは１５００℃以下が好ましい範囲である。このような熱処理条件において、昇温速度、冷却速度、熱処理時間などは目的に応じて任意に設定する事ができる。また、比較的低温領域で熱処理した後、所定の温度に昇温する事もできる。
【００２５】
なお、本工程に用いる反応機は回分式でも連続式でも又、一基でも複数基でもよい。
Ｄ．粉体加工工程
こうして炭素化工程において炭素質物（Ｓ）が炭素化し、炭素質物（Ｎ）表面の一部あるいは全体を被覆した状態で複合化した生成物は本工程において、必要に応じて粉砕、解砕、分級処理など粉体加工処理を施され、非水溶媒二次電池用電極材料とする。
【００２６】
なお、粉体加工工程は脱揮・重縮合反応工程と炭素化工程との間に挿入することもできる。
（４）複合炭素質物
本願発明の複合炭素質物は全体として粒状、繊維状などの任意の形状を取りえるが粒状であることが好ましい。粒状の場合、体積平均粒径が１〜１００μｍ、好ましくは３〜３０μｍ、特に好ましくは５〜２５μｍである。繊維状の場合は、直径が好ましくは０．５〜２５μｍ、好ましくは１〜２０μｍ、特に好ましくは２〜１０μｍであり、長さは好ましくは１０ｍｍ以下、好ましくは５ｍｍ以下である。
【００２７】
又、本願発明による複合炭素質物のＢＥＴ法を用いて測定した比表面積は好ましくは１〜１０ｍ²／ｇ、特に好ましくは２〜６ｍ²／ｇの範囲に入ることが好ましく、特に核とした黒鉛性炭素質物（Ｎ）のＢＥＴ比表面積に対し、生成した複合炭素質物のＢＥＴ比表面積が１／４以上３／４以下好ましくは１／３以上２／３以下の範囲に入るものが好ましい。
【００２８】
又、本願発明の複合炭素質物は、波長５１４５Åのアルゴンイオンレーザー光を用いたラマンスペクトル分析において、下記のようなスペクトルの特徴を有することが好ましい。
尚、本発明においてピーク強度及びスペクトル強度積分値は下記条件による値である。すなわち、１５８０±１００ｃｍ^-1の波長域にあるピークＰ_Aの強度をＩ_A、スペクトル強度の積分値をＹ_Aとし、１３６０±１００ｃｍ^-1の範囲の波長域にあるピークＰ_Bの強度をＩ_B、スペクトル強度の積分値をＹ_Bとする。
【００２９】
本願発明の複合炭素質物は両者のピーク強度Ｉ_BとＩ_Aの比、即ちＲ＝Ｉ_B／Ｉ_Aが、該複合炭素質物の核として用いた黒鉛性炭素質物のＲ値より大であり、かつ０．４未満であることが好ましい。特に好ましくは０．１１〜０．３３の範囲、更に好ましくは０．１２〜０．２８の範囲であることが、良好な電気性能を得る上で好ましい。又、スペクトル強度の積分値Ｙ_BとＹ_Aの比、即ちＧ＝Ｙ_B／Ｙ_A値としては、該複合炭素質物の核として用いた黒鉛性炭素質物のＧ値より大であり、かつ０．７５未満であることが好ましい。特に好ましくは０．２６〜０．７４、更に好ましくは０．３〜０．６８の範囲であることが好ましい。
【００３０】
尚、黒鉛のみの電極材料のＲ値は約０．１程度、Ｇ値は０．２５程度であり、一方、従来の明確な複相を有する複合炭素質物のＲ値は０．４以上、Ｇ値は０．７５程度であった。
一方、本願発明の複合炭素質物は、ＣｕＫα線を線源としたＸ線広角回折の回折図において、黒鉛性炭素質物（Ｎ）に由来するピークを見かけ状の単一ピークとして、その低角側に炭素質物（Ｓ）に由来する非常にブロードなピークを肩状に有する回折図を示し、黒鉛性炭素質物（Ｎ）と炭素質物（Ｓ）の量比に大きな差があるため、統計的な処理では正確な該ピークの分離が出来ない傾向にある。特に好ましくい態様としては、Ｘ線回折図形として、核として用いた黒鉛性炭素質物との結晶構造の変化がとらえられないことが好ましい。即ち、測定上の誤差を考慮すると核となる黒鉛性炭素質物と実質的に等しい半値幅を有することが好ましい。この半値幅はＸ線回折スペクトルを非対象ピアソン〓関数を用いてプロファイルフィテング化してスムーズにしたカーブから測定する。即ち本発明の好ましい態様としては、その半値幅値が、その核として用いた黒鉛性炭素質物（Ｎ）の半値幅値の±３σ（σは１０回測定したときの標準偏差）に入るものを用いることが挙げられる。
（５）二次電池
上記複合炭素質物は、公知の方法に従い高分子結着剤との混合物、あるいは活物質と合金を形成しうる金属、又は活物質と該金属との合金を配合してなる混合物からなる電極材料とし、該電極材料をそのまま、ロール成形、圧縮成形などの方法で電極の形状に成形して、負極として用いることができる。本願発明の二次電池の構成としては、上記のようにして得られた負極と、公知の任意の正極と、該正極と負極の間に介在し電解液を保持する公知の任意のセパレーター、例えばポリエチレン、ポリプロピレンのようなポリオレフィン系樹脂の不織布などを採用することができる。又、これに含浸させる電解液としても、公知の任意の電解液、例えば、エチレンカーボネート、プロピレンカーボネート、１，３−ジオキソラン、１，２−ジメトキシエタン、２−メチルテトラヒドロフランなどの非プロトン性有機溶媒に、ＬｉＣｌＯ₄、ＬｉＢＦ₄、ＬｉＡｓＦ₆、ＬｉＰＦ₆、ＬｉＳＯ₃ＣＦ₃、ＬｉＮ（ＳＯ₂ＣＦ₃）₂などの電解質を溶解させた所定濃度の非水電解液を用いることができる。
【００３１】
【実施例】
次に実施例により本発明を更に詳細に説明するが、本発明はこれらの例によってなんら限定されるものではない。
［実施例１］
（１）混合工程
内容積２０リットルのステンレスタンクに炭素質物（Ｎ）として人造黒鉛粉末（ＬＯＮＺＡ社製ＫＳ−４４：ｄ００２＝０．３３６ｍ，Ｌｃ＝１００ｎｍ以上，平均体積粒径１９μｍ）を３ｋｇを投入し、炭素質物（Ｓ）としてナフサ分解時に得られるエチレンヘビーエンドタール（三菱化学（株）製：５０℃における粘度５０ｃｐを）１ｋｇを加えて、更に希釈剤としてハードアルキルベンゼン（三菱化学社製）を３．５ｋｇ加え、ハンドミキサーにて２０分撹拌した。更に８０℃の温水でステンレス容器を湯浴し、更に１０分間同様な手法で撹拌したところ、調整されたスラリーの流動性から目視においても混合度が向上していることが確認された。なお、得られたスラリーの粘度は３２１０ｃｐであった。
（２）脱揮・重縮合反応工程
混合工程で得られたスラリー状の混合物を計量ギアポンプを用いて、図１に概略を示す上記明細書中で説明した（ａ）タイプの装置、即ち栗本鉄工所（株）製ＫＲＣＳ１リアクタ１台に３．２Ｋｇ／ｈで供給し、エチレンヘビーエンドタールの熱処理ピッチ化反応を行った。リアクタ内温を４３０℃に保ち、更に減圧度を８７．９９×１０３ Ｐａ（６６０ｔｏｒｒ）とし、脱気及び脱揮を行い、エチレンヘビーエンドタールの軽質留分と希釈剤の除去を行った。生成物を、ＫＲＣリアクタ出口より、ペレット状で１．５Ｋｇ／ｈで回収した。こうして炭素質物粒子と熱処理ピッチの複合物を得た。なお、反応に用いたＫＲＣリアクターには、直径２５ｍｍの凸レンズ型パドルを４５度ずらして計１５枚取り付け使用した。
（３）炭素化工程
上記、炭素質物粒子と十分に芳香族化したピッチの複合粉粒体を回分式加熱炉で熱処理した。複合粉粒体を黒鉛容器にいれた状態で内熱式加熱炉に入れ、窒素ガスを５リットル／分の流量下で３時間で９５０℃まで昇温し、１時間保持した。その後、室温まで冷却して被覆相が炭素化した複合物を得た。
（４）粉体処理工程
炭素化工程で得られた複合物を衝撃式粉砕機を用いて解砕し、一定の粒径分布をもった炭素系複合粉末を得た。 なお、黒鉛１００重量部に対する有機物の炭化物量を表に示す。
（５）炭素系複合粉末の分析
下記に手法に従って分析を行った。結果を表１に示す。
（５−１）（００２）面の面間隔（ｄ００２）、結晶子の大きさＬｃ
炭素質材料が粉末の場合にはそのまま、微小片状の場合にはメノウ乳鉢で粉末化し、試料に対して約１５ｗｔ％のＸ線標準高純度シリコン粉末を加えて混合し、試料セルに詰め、グラファイトモノクロメーターで単色化したＣｕＫα線を線源とし、反射式ディフラクトメーター法によって広角Ｘ線回折曲線を測定した。得られたＸ線回折曲線は異なる結晶化度に由来するふたつのピークが重なりあった形状を呈しており、黒鉛性炭素質物に由来するピークを見掛け状の単一ピークとして、その低角側に炭素質被覆層に由来する非常にブロードなピークが肩状に現れていた。但し、複合炭素質物の黒鉛性炭素質物と表面に付着した炭素質物の量比に大きさ差があるため、統計的な処理で正確なピーク分離を行うことは不可能であった。
（５−２）ラマンスペクトル分析：
波長５１４．５ｎｍのアルゴンイオンレーザー光を用いたラマンスペクトル分析において、１５８０ｃｍ−１の付近のピークＰＡの強度ＩＡ、１３６０ｃｍ−１の範囲のピークＰＢの強度ＩＢを測定し、その強度の比Ｒ＝ＩＢ／ＩＡを測定した。黒鉛ＫＳ−４４のＲ値は０．１２であり、表面が被覆されていると判断された。
（５−３）体積基準平均粒径
堀場製作所社製レーザー回折式粒度分布計「ＬＡ−７００」を用い、分散媒にエタノールを使用して体積基準平均粒径（メジアン径）を測定した。
（６）電極性能評価
（６−１）電極成形体の作成
熱可塑性エラストマー（スチレン・エチレン・ブチレン・スチレン・ブロックコポリマー）のトルエン溶液およびポリエチレン粉末を加えてかくはんし、スラリーを得た。重量比は、炭素質物９３ｗｔ％、熱可塑性エラストマー（固形分）４ｗｔ％、ポリエチレン粉末３ｗｔ％とした。このスラリーを銅箔上に塗布し、８０℃で予備乾燥を行った。さらに銅箔に圧着させたのち、直径２０ｍｍの円盤上に打ち抜き、１１０℃で減圧乾燥をして電極とした。
（６−２）濡れの評価
電解液との濡れの大きさを比較するために、（６−１）で作成した電極の接触角の測定をゴニオメーター式接触角測定器を用いて行った。測定には純度９９．９％のプロピレンカーボネートを単一溶媒として使用した。結果は、接触角が小さいために測定不能であった。これは溶媒と電極との親和性が非常に良いことを示している。プロピレンカーボネートを使用した理由は単独のエチレンカーボネートは室温で固体であり、エチレンカーボネートを液体とするには副溶媒として他成分を混合しなければならず、実験条件を単純化出来ないためである。接触角の比較には実験条件は極力単純であるべきであり、室温で液体であるプロピレンカーボネートを選択した。
（６−３）半電池による電極評価
上記電極に対し、電解液を含浸させたセパレーターをはさみ、リチウム金属電極に対抗させたコイン型セルを作成し、充放電試験を行った。電解液としては、エチレンカーボネートとジエチレンカーボネートを重量比１：１の比率で混合した溶媒に過塩素酸リチウムを１．５モル／リットルの割合で溶解させたものを用いた。
【００３２】
充放電試験は電流値を０．２ｍＡとし、両電極間の電位差が０Ｖになるまで充電を行い、１．５Ｖまで放電を行った。その結果を表２に示す。表中の不可逆容量は、充電容量から放電容量の値を差し引いて求めた値であり、充放電効率は放電容量を充電容量で除した値である。
［実施例２］
炭化工程で最高処理温度を１２００℃とした以外は、実施例１と同様の操作を行った。尚、この複合炭素質物のＸ線回折スペクトル図を図３に示す。このグラフより半値幅は０．２２３°であることがわかった。後述する比較例４に示す核となる黒鉛性炭素質物のＸ線回折スペクトルの半値幅は０．２１６°であり、半値幅の標準偏差σは３．１２×１０^-3°であるので、実施例２の複合炭素質物の半値幅は核として用いた黒鉛性炭素質物の半値幅±３σの範囲に入ることが確認される。
［実施例３］
炭化工程で最高処理温度を２０００℃とした以外は、実施例１と同様の操作を行った。
［実施例４］
炭化工程で最高処理温度を２４００℃とした以外は、実施例１と同様の操作を行った。
［実施例５］
（１）混合工程
図２に概略を示す上記明細書中（ｂ）タイプと記載した装置、即ちレーディゲ社製レ−ディゲミキサー Ｍ−２０型（内容積２０リットル）を用いて、混合工程および脱揮工程を実施した。まず、原料供給口より、人造黒鉛粉末（ＬＯＮＺＡ社製ＫＳ−２５）３Ｋｇとエチレンヘビーエンドタール（三菱化学（株）製：５０℃における粘度５０ｃｐを）製）１Ｋｇ、更に希釈剤としてトルエン２．８ｋｇを投入し、運転を開始した。運転条件は、すき型撹拌翼の回転数が２００ｒｐｍ、解砕翼の回転数が２０００ｒｐｍであり、装置内温度は室温であった。この操作を１０分行った。
（２）脱揮工程
ミキサーのジャケットに温水を流し、１００℃で加温した。次に装置内部を徐々に減圧し、最終的に内部を１３．３３×１０３ Ｐａ（１００ｔｏｒｒ）とし、脱気及び脱揮を進行させ、エチレンヘビーエンドタールの軽質留分と希釈剤の除去を行った。しかる後に温度を室温まで下げ、人造黒鉛粉末にエチレンヘビーエンドタールが付着・含浸された複合物を粉末状で得た。
（３）炭素化工程および粉体処理工程
炭化工程で最高処理温度を１２００℃とした以外は、実施例１と同様の操作を行った。
（４）炭素系複合粉末の分析・評価
実施例１と同様に行った。評価結果を表１、２に示した。
［実施例６］
実施例５と同様にレーディゲ 社製レ−ディゲミキサー Ｍ−２０型（内容積２０リットル）を用いて、混合工程および脱揮工程を実施した。まず、原料供給口より、人造黒鉛粉末（ＬＯＮＺＡ社製ＫＳ−４４）３Ｋｇとエチレンヘビーエンドタール（三菱化学（株）製：５０℃における粘度５０ｃｐを）製）０．６Ｋｇ、更に希釈剤としてトルエン３．０ｋｇを投入した。この後の操作は 実施例１と同様の操作を行った。
［実施例７］
実施例５と同様にレーディゲ 社製レ−ディゲミキサー Ｍ−２０型（内容積２０リットル）を用いて、混合工程および脱揮工程を実施した。まず、原料供給口より、人造黒鉛粉末（ＬＯＮＺＡ社製ＫＳ−４４）３Ｋｇとエチレンヘビーエンドタール（三菱化学（株）製：５０℃における粘度５０ｃｐを）製）０．６Ｋｇ、更に希釈剤としてトルエン３．０ｋｇを投入した。この後の操作は炭化工程で最高処理温度を１２００℃とした以外は実施例１と同様の操作を行った。
［実施例８］
実施例５と同様にレーディゲ 社製レ−ディゲミキサー Ｍ−２０型（内容積２０リットル）を用いて、混合工程および脱揮工程を実施した。まず、原料供給口より、人造黒鉛粉末（ＬＯＮＺＡ社製ＫＳ−４４）３Ｋｇとエチレンヘビーエンドタール（三菱化学（株）製：５０℃における粘度５０ｃｐを）製）０．２Ｋｇ、更に希釈剤としてトルエン３．２ｋｇを投入した。この後の操作は実施例１と同様の操作を行った。
［実施例９］
実施例５と同様にレーディゲ 社製レ−ディゲミキサー Ｍ−２０型（内容積２０リットル）を用いて、混合工程および脱揮工程を実施した。まず、原料供給口より、人造黒鉛粉末（ＬＯＮＺＡ社製ＫＳ−４４）３Ｋｇとエチレンヘビーエンドタール（三菱化学（株）製：５０℃における粘度５０ｃｐを）製）０．２Ｋｇ、更に希釈剤としてトルエン３．２ｋｇを投入した。この後の操作は炭化工程で最高処理温度を１２００℃とした以外は実施例１と同様の操作を行った。
［実施例１０］
（１）混合工程
実施例５と同様、レ−ディゲミキサー Ｍ−２０型（内容積２０ｌ）を用いて、混合工程および脱揮工程を実施した。
【００３３】
まず、原料供給口より、人造黒鉛粉末（ＬＯＮＺＡ社製ＫＳ−４４）３ｋｇとコールタールピッチ（新日本鉄化学（株）製）０．２７ｋｇ、希釈溶剤としてピリジンを３．０ｋｇを投入した。この後の操作は実施例１と同様の操作を行った。
（２）脱揮・重縮合反応工程
次に内部を窒素ガス雰囲気に置換し、昇温を開始した。８０分かけて内温を１１０℃とし、更に９０分間の混合を行った。その後、内部を徐々に減圧し、最終的には３０．６６×１０³Ｐａ（２３０ｔｏｒｒ）とした。この間に３０分を要した。こうして溶剤を回収した後、徐々に内温を下降させ、内容物を排出口より粉末状態で回収した。こうして黒鉛粉末にコールタールピッチ成分が付着・含浸した複合物を得た。
この後の操作は炭化工程で最高処理温度を１２００℃とした以外は実施例１と同様の操作を行った。
［実施例１１］
最終的に炭素質物（Ｓ）となる有機物に分解系の石油ピッチとして、ＦＣＣデカントオイルを用いて、実施例１と同様な手法で試料を作成した。
【００３４】
まず、内容積２０リットルのステンレスタンクに炭素質物（Ｎ）として人造黒鉛粉末（ＬＯＮＺＡ社製ＫＳ−２５：ｄ００２＝０．３３６ｍ，Ｌｃ＝１００ｎｍ以上，平均体積粒径１０μｍ）を３Ｋｇを投入し、炭素質物（Ｓ）の原料としてＦＣＣデカントオイル１ｋｇ、希釈溶剤としてハードアルキルベンゼンを加えて、ハンドミキサーにて２０分撹拌した。更に８０℃の温水でステンレス容器を湯浴し、更に１０分間同様な手法で撹拌した。
以下同様な方法により、炭素系複合粉末を得た。分析・電極評価も他の実施例と同様の手法に従い行った。
［実施例１２］
（１）混合工程
内容積２０リットルのステンレスタンクに炭素質物（Ｎ）として人造黒鉛粉末（ＬＯＮＺＡ社製ＫＳ−４４：ｄ００２＝０．３３６ｍ，Ｌｃ＝１００ｎｍ以上，平均体積粒径１９μｍ）を３ｋｇを投入し、炭素質物（Ｓ）としてナフサ分解時に得られるエチレンヘビーエンドタール（三菱化学（株）製：５０℃における粘度５０ｃｐを）１ｋｇを加えて、更に希釈剤としてトルエンを３．０ｋｇ加え、ハンドミキサーにて２０分撹拌した。更に８０℃の温水でステンレス容器を湯浴し、更に１０分間同様な手法で撹拌したところ、調整されたスラリーの流動性から目視においても混合度が向上していることが確認された。なお、得られたスラリーの粘度は３５００ｃｐであった。
（２）脱揮・重縮合反応工程
混合工程で得られたスラリー状の混合物を高粘性用スラリーポンプを用いて、栗本鉄工所（株）製ＳＣプロセッサＳＣＰ−１００型１台に７５Ｋｇ／ｈで供給し、エチレンヘビーエンドタールとトルエンの蒸留化反応を行った。リアクタ内温を１９０℃に保ち、更に減圧度を８７．９９×１０３ Ｐａ（６６０ｔｏｒｒ）とし、脱気及び脱揮を行い、エチレンヘビーエンドタールの軽質留分と希釈剤の除去を行った。生成物を、ＫＲＣリアクタ出口より、ペレット状で３６Ｋｇ／ｈで回収した。こうして炭素質物粒子とエチレンヘビーエンドタールの残留分との複合物を得た。
【００３５】
この後の操作は炭化工程で最高処理温度を１２００℃とした以外は実施例１と同様の操作を行った。
［比較例１］
実施例１の場合と同様な手法で黒鉛性炭素質物に付着した有機物が過剰に多い状態の複合炭素質粉末を作成し、評価を行った。
【００３６】
まず、内容積２０リットルのステンレスタンクに炭素質物（Ｎ）として人造黒鉛粉末（ＬＯＮＺＡ社製ＫＳ−４４：ｄ００２＝０．３３６ｍ，Ｌｃ＝１００ｎｍ以上，平均体積粒径１９μｍ）を３Ｋｇを投入し、炭素質物（Ｓ）の原料としてナフサ分解時に得られるエチレンヘビーエンドタール（三菱化学（株）製：５０℃における粘度５０ｃｐを）７Ｋｇを加えて、ハンドミキサーにて２０分撹拌した。更に８０℃の温水でステンレス容器を湯浴し、更に１０分間同様な手法で撹拌した。
（２）脱揮・重縮合反応工程
混合工程で得られたスラリー状の混合物を計量ギアポンプを用いて、栗本鉄工所（株）製ＫＲＣＳ１リアクタ１台に３．１Ｋｇ／ｈで供給し、エチレンヘビーエンドタールの熱処理ピッチ化反応を行った。リアクタ内温を４３０℃に保ち、更に減圧度を８７．９９×１０３ Ｐａ（６６０ｔｏｒｒ）とし、脱気及び脱揮を行い、エチレンヘビーエンドタールの軽質留分の除去を行った。高粘性を示す半固溶体である生成物を、ＫＲＣリアクタ出口より、ペレット状で１．５Ｋｇ／ｈで回収した。こうして炭素質物粒子と熱処理ピッチの複合物を得た。なお、反応に用いたＫＲＣリアクターには、直径２５ｍｍの凸レンズ型パドルを４５度ずらして計１５枚取り付け使用した。
【００３７】
この後の操作は炭化工程で最高処理温度を１２００℃とした以外は実施例１と同様の操作を行った。
尚、この複合炭素質物のＸ線回折スペクトル図を図３に示す。このグラフより比較例１の複合炭素質物の半値幅は０．２３０°であることがわかった。後述する比較例４に示す核となる黒鉛性炭素質物のＸ線回折スペクトルの半値幅は０．２１６°であり、半値幅の標準偏差σは３．１２×１０^-3°であるので、比較例１の複合炭素質物の半値幅は核として用いた黒鉛性炭素質物の半値幅±３σの範囲外となることが確認される。
［比較例２］
まず、内容積２０リットルのステンレスタンクに炭素質物（Ｎ）として人造黒鉛粉末（ＬＯＮＺＡ社製ＫＳ−４４：ｄ００２＝０．３３６ｍ，Ｌｃ＝１００ｎｍ以上，平均体積粒径１９μｍ）を３Ｋｇを投入し、炭素質物（Ｓ）の原料としてナフサ分解時に得られるエチレンヘビーエンドタール（三菱化学（株）製：５０℃における粘度５０ｃｐを）４．２Ｋｇ、更に希釈剤としてハードアルキルベンゼン（三菱化学社製）を３．０ｋｇ加え、ハンドミキサーにて２０分撹拌した。更に８０℃の温水でステンレス容器を湯浴し、更に１０分間同様な手法で撹拌した。この後の操作は炭化工程で最高処理温度を１２００℃とした以外は実施例１と同様の操作を行った。
［比較例３］
実施例５の場合と同様な手法で黒鉛性炭素質物に付着した有機物が過剰に多い状態の複合炭素質粉末を作成し、評価を行った。
（１）混合工程
まず、原料供給口より、人造黒鉛粉末（ＬＯＮＺＡ社製ＫＳ−４４）３ｋｇとコールタールピッチ（新日本鉄化学（株）製）１．６ｋｇ、希釈溶剤としてピリジンを３ｋｇ投入し、運転を開始した。運転条件は、すき型撹拌翼の回転数が２３０ｒｐｍ、解砕翼の回転数が３０００ｒｐｍであり、装置内温度は３０℃であった。
（２）脱揮・重縮合反応工程
次に内部を窒素ガス雰囲気に置換し、昇温を開始した。８０分かけて内温を１１０℃とし、更に９０分間の混合を行った。その後、内部を徐々に減圧し、最終的には３０．６６×１０³Ｐａ（２３０ｔｏｒｒ）とした。この間に４０分を要した。こうして溶剤を回収した後、徐々に内温を下降させ、内容物を排出口より造粒された状態で回収した。黒鉛粉末とコールタールピッチとの複合物を直径約２ｍｍのほぼ均一な造粒物として得ることができた。
【００３８】
この後の操作は炭化工程で最高処理温度を１２００℃とした以外は実施例１と同様の操作を行った。
［比較例４］
表面修飾を施さない人造黒鉛粉末としてＬＯＮＺＡ社製人造黒鉛ＫＳ−４４を用いて比較実験を行った。尚、この黒鉛のＸ線回折スペクトル図を図３に示す。このグラフより比較例４の黒鉛の半値幅は０．２１６°であることがわかった。尚、半値幅の標準偏差σは３．１２×１０^-3°である。
［比較例５］
表面修飾を施さない人造黒鉛粉末としてＬＯＮＺＡ社製人造黒鉛ＫＳ−２５を用いて比較実験を行った。
［比較例６］
表面修飾を施さない人造黒鉛粉末として関西熱化学社製の天然黒鉛ＮＧ−７を用いて比較実験を行った。
【００３９】
【表１】

【００４０】
【表２】

【００４１】
【発明の効果】
以上説明したように、本発明の非水溶媒二次電池電極材料によれば、黒鉛並の高い放電容量を保持しつつ、かつ不可逆容量が非常に低く抑えられ、充電効率が優れるという良好な電気特性が得られ、更には電解液に対する安定性が向上した非水溶媒二次電池を提供することができる。
【００４２】
又、本願発明の製造方法によれば、かかる高性能の均一な性能の複合炭素質物をを安定的に効率よく製造することができる。
【図面の簡単な説明】
【図１】本願発明に用いる（ａ）タイプの反応装置の一例を示す図
【図２】本願発明に用いる（ｂ）タイプの反応装置の一例を示す図
【図３】実施例２、比較例１、比較例４で用いた黒鉛性炭素質物又は黒鉛のＸ線回折スペクトル図を示す図
【符号の説明】
１・・シャフト、２・・パドル、３・・反応室、
１１・・シャフト、１２・・パドル、１３・・反応室、１４・・スクリュー型解砕翼[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrode material used for a nonaqueous solvent secondary battery and a manufacturing method thereof, and more particularly to an electrode material having a multiphase structure and a manufacturing method thereof.
[0002]
[Prior art]
In recent years, a secondary battery having a high capacity has been required along with miniaturization of electronic equipment. In particular, non-aqueous solvent secondary batteries with higher energy density have attracted attention as compared with nickel-cadmium and nickel-hydrogen batteries. As the negative electrode material, metals and graphite have been studied so far. However, the metal electrode has a problem that when charging and discharging are repeated, the metal in the solvent is deposited in a dendrite shape, and eventually both electrodes are short-circuited. In addition, since graphite allows metal ions to enter and exit between the layers, there is no short circuit problem, but in addition to decomposing the propylene carbonate electrolyte, the charge / discharge cycle characteristics of the ethylene carbonate electrolyte are poor. There is.
[0003]
On the other hand, the use of a carbonaceous material having a multiphase structure has also been studied. This is because of the advantages (high capacity and small irreversible capacity) and disadvantages (decomposes propylene carbonate electrolyte) of carbonaceous material with high crystallinity, and the advantage of carbonaceous material with low crystallinity (excellent stability with electrolyte). ) And shortcomings (small capacity and large irreversible capacity), based on the idea of making up for each other while taking advantage of each other's strengths. For example, Japanese Patent Laid-Open No. 4-370662 previously proposed by the present inventors shows that carbonaceous material particles composed of a core composed of a carbonaceous material having a high graphite property and a surface layer composed of a carbonaceous material having a low graphite property are used. ing. However, in the prior art, it was considered that a uniform layer could not be obtained unless it was a relatively thick surface layer due to manufacturing restrictions. For example, as a specific example, the ratio of the core to the surface layer was 50 parts by weight to 50 weights. Part example (Example 1), 53 to 47 example (Example 2), 65 to 35 example (Example 3), with a relatively thick surface layer, clearly multiphase A composite carbonaceous material consisting of
[0004]
[Problems to be solved by the invention]
However, as a result of intensive investigations on electrode materials having various physical properties, the present inventors have found that a conventional composite carbonaceous material having a relatively thick surface layer and clearly consisting of multiple layers is preferable as a secondary battery electrode material. Contrary to the technical idea that has been made, it is surprising to use an electrode material in which a trace amount (thin) organic carbide adhering to the carbonaceous carbonaceous material is in a specific range. Compared to graphite alone and conventional clear multiphase composite carbonaceous materials, non-aqueous solvents with high electrical capacity, low retention, extremely good electrical performance, and high safety against electrolytes The inventors have found that a secondary battery can be obtained and have reached the present invention.
[0005]
Further, the inventors have found a specific manufacturing method for obtaining such a specific electrode material, and found that an electrode material having uniform performance can be stably and efficiently manufactured by such a method, thereby completing the present invention.
[0006]
[Means for Solving the Problems]
That is, the gist of the present invention is that an organic carbide that is 12 parts by weight or less and 0.1 parts by weight or more as a residual carbon amount with respect to 100 parts by weight of the graphitic carbonaceous material is adhered to the surface of the graphitic carbonaceous material. A slurry prepared by adding an aromatic organic solvent to an electrode material for a non-aqueous solvent secondary battery, or a mixture of graphitic carbonaceous particles and an organic material, and adjusting the viscosity to 10,000 cp or less. And a reaction chamber having a paddle that is rotated by a shaft inside, and the inner wall surface of the reaction chamber is formed substantially along the outermost line of the rotation of the paddle, and has a mechanism for degassing the solvent. The mixture is introduced into a mixing and stirring device and heated to a temperature of not lower than the boiling point of the solvent and lower than 600 ° C. while stirring to produce a solid intermediate substance. The intermediate substance is heated to 600 ° C. or higher in an inert gas atmosphere. Heated to carbonized It consists in the manufacturing method of a non-aqueous solvent secondary battery electrode material characterized by having that process.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The electrode material for a secondary battery of the present invention is a composite carbonaceous material obtained by adhering an organic carbide to the surface of a graphitic carbonaceous material.
(1) Selection of raw materials
In the present invention, the graphitic carbonaceous material (hereinafter also referred to as carbonaceous material (N)) that finally forms nuclei has a (002) plane spacing d002 of 0.00 as a peak of diffraction lines corresponding to the structure. It is preferably 345 nm or less, preferably 0.340 nm or less, and the crystallite size Lc in the c-axis direction is 15 nm or more, preferably 50 nm or more, more preferably Lc is 80 nm or more. The shape of can be any shape such as granular or fibrous, but is preferably in the form of particles, so long as it satisfies the volume average particle size of 30 μm or less, preferably 28 μm or less, 5 μm or more. In addition to particles, carbon fibers of pitch, polyacrylonitrile, mesophase pitch, and vapor phase growth may be used. Can. These may be used alone or in combination of two or more.
[0008]
As a specific method for preparing the carbonaceous material (N),
(A) Carbonization and graphitization are performed by heating a melt-soluble organic substance, a thermosetting polymer, etc. in an inert gas atmosphere or in a vacuum at a temperature of 1500 to 3000 ° C., preferably 2000 to 3000 ° C. How to do.
(B) A method in which an already-made carbonaceous material such as carbon black or coke is further heat-treated to cause graphitization to proceed appropriately.
(C) A method of using artificial graphite, natural graphite, vapor-grown graphite whisker, or carbon fiber as it is, or adjusting the particle diameter and fiber length and then using it in powder form.
Etc. can be used.
[0009]
On the other hand, liquid carbonization reaction such as heavy oil is used as the raw material for organic carbonized material (hereinafter referred to as carbonaceous material (S)) that is finally attached to the surface of carbonaceous material (N) and covers the core. Organic substances such as organic substances with a solid-phase carbonization reaction such as thermosetting resins or mixtures thereof (see “Chemicals and Industry of Carbon Materials” by Isao Mochida, published by Asakura Shoten).
[0010]
Heavy oils include coal tar pitch from soft pitch to hard pitch, coal heavy oil such as coal liquefied oil, DC heavy oil such as asphaltene, ethylene heavy by-product during thermal decomposition of crude oil, naphtha, etc. Use heat-treated pitches such as ethylene tar pitch, FCC decant oil, Kureha pitch, Ashland pitch, etc. obtained by heat-treating petroleum heavy oil such as end tar and heavy oil such as cracked heavy oil and cracked heavy oil. it can.
[0011]
In addition, as organic substances that advance carbonization in the solid phase, natural polymers such as cellulose, thermosetting resin raw materials that advance carbonization via heat-cured furfuryl alcohol resin, furfuryl alcohol, phenol-formaldehyde resin, etc. Can be given.
(2) Mixing ratio
In the present invention, usually, a mixture of such graphitic carbonaceous particles (N) and an organic substance is heated to obtain an intermediate substance, and then carbonized and fired and pulverized to finally produce a graphitic carbonaceous substance (N). A composite carbonaceous material having an organic carbide (S) attached to the surface of the carbonaceous material is obtained, but the amount of the organic carbide on the surface of the graphitic carbonaceous material is the minimum necessary. That is, the amount of residual carbon with respect to 100 parts by weight of the graphitic carbonaceous material is 12 parts by weight or less, preferably 0.1 parts by weight or more, preferably 8 parts by weight or less, 0.5 parts by weight or more, more preferably 7.0 parts by weight or less. Adhere organic carbide that is more than part by weight.
[0012]
The amount of remaining coal depends on the type of organic matter and the mixing ratio of the organic matter. Among the test methods defined in advance by JIS K2270, the remaining coal rate of the organic matter determined according to the micro method is measured, The kind of organic substance in which the weight of the carbide obtained by multiplying the weight of the organic substance used by the following (formula 1) is 12 parts by weight or less and 0.1 parts by weight or more with respect to 100 parts by weight of the graphitic carbonaceous material (N). The organic matter is adsorbed and impregnated on the surface of the graphitic carbonaceous material.
[0013]
[Expression 1]

In the present invention, if the residual carbon ratio is too small, it is considered that the filling of the organic material into the pores of the graphitic carbonaceous material becomes insufficient, and a. The graphite is easily exposed on the surface of the carbonaceous material having a multiphase structure, so that the stability with the electrolytic solution is reduced; b. The gas remaining in the pores may be ejected during the heat treatment process to destroy the multiphase structure; c. If pores remain, it may cause deterioration of conductivity, hinder metal ion migration, or low wettability of the composite carbonaceous material, which is an active material, to the electrolytic solution. There arises a problem that the surface of the carbonaceous material on which the slag is performed is not uniformly used for the exchange of metal ions. On the other hand, if the amount of residual carbon is too large, it is considered that the physical properties of the composite carbonaceous material change due to the organic material more than the organic material is filled into the pores of the graphitic carbonaceous material. The capacity decreases, the charge / discharge efficiency decreases, and the characteristics of the graphitic carbonaceous material, which has the maximum theoretical electrode capacity, cannot be used effectively.
[0014]
In the production method of the present invention, the graphitic carbonaceous material (N) is mixed in an organic material, preferably an organic material having a viscosity at 50 ° C. of 200 cp or less, dispersed, and brought into contact with the organic material, so An operation of substituting the surface of the graphitic carbonaceous particles and the inside of the pores with a polycyclic aromatic molecule contained in the refined oil, preferably a polycyclic aromatic oligomer having a higher molecular weight is performed. However, in the case of using heavy oil having a viscosity of more than 200 cp at 50 ° C., an aromatic solvent such as toluene, xylene, alkylbenzene or the like is used in order to perform adsorption and impregnation of an organic substance on a homogeneous and efficient graphitic carbonaceous material. It is preferable to add a solvent made of a heterocyclic compound such as a quinoline organic solvent or quinoline or pyridine to the mixture of the graphitic carbonaceous material (N) and the organic material. An aromatic organic solvent is preferred for the present invention.
[0015]
Furthermore, in the present invention, it is also useful to previously treat the graphitic carbonaceous material (N) with a solvent. The carbonaceous material particles (N) are immersed in an aromatic solvent, and the surface and pores are replaced with the solvent, and then the carbonaceous material particles separated from the excess solvent are used, whereby the carbonaceous material particles are used. The effect of improving the “wetting” of the particles (N) with respect to the organic matter can be obtained. As an addition ratio of the organic solvent, it is desirable to add it until the state in which the solvent is added to the mixture of the graphitic carbonaceous material and the organic material becomes a slurry. The slurry viscosity at 50 ° C. is preferably 10,000 cp or less, more preferably 5000 cp or less, and still more preferably 1000 cp or less. When the organic substance is a solid, it is dissolved by a solvent, and when it is a liquid, it is necessary to adjust the viscosity by dilution. When dissolving the organic matter, it is not always necessary to dissolve all the components of the heavy oil, as long as it is liquefied within a predetermined viscosity range. If the viscosity of the heavy oil exceeds 10 Pas (10000 cP), the electrode performance varies, which is not preferable. This is presumably because the organic matter is less likely to be filled into the pores present in the carbonaceous material (N).
[0016]
If this filling is insufficient, problems such as a, b and c are likely to occur.
(3) Manufacturing method
On the other hand, the manufacturing method of this invention for obtaining this composite carbonaceous material of this invention is demonstrated below.
The method for producing a composite carbonaceous material of the present invention mainly comprises the following steps.
(A) A step of mixing the carbonaceous material (N) with an organic material and preferably a solvent to obtain a mixture.
(B) A step of heating the mixture with stirring to obtain an intermediate substance.
(C) A step of heating the intermediate substance to 600 ° C. or more, preferably 2500 ° C. or less in an inert gas atmosphere to obtain a carbonized substance.
(D) A step of powder-processing the carbonized material.
A. Mixing process
In the first step of the present invention, the carbonaceous material (N) and the organic material, and preferably the aforementioned solvent are added and mixed. The mixing step may be performed by either a batch type or continuous type device. Moreover, you may carry out at room temperature and you may carry out by heating a reaction tank. By heating the reaction vessel, the viscosity of the mixture can be reduced, the load on the apparatus can be reduced, and the mixing efficiency can be increased. Furthermore, the defoaming effect from the fine powder can be enhanced and the dispersibility can be improved by reducing the pressure in the tank during mixing.
[0017]
In the case of the batch type, the mixing device may be composed of one mixer equipped with a stirring blade, or may be composed of a plurality of units to improve the dispersibility sequentially. Batch mixers include two mixers that have a structure in which two frame-type blades rotate while performing planetary motion in a fixed tank, a dissolver that is a high-speed high-shear mixer, and a butterfly mixer for high viscosity. A total of 3 so-called kneader-type devices with a structure in which a single blade stirs and disperses the tank, a sigma-type stirrer rotating along the side surface of the semi-cylindrical mixing tank, and a total of 3 stirrers A trimix type apparatus using a shaft, a so-called bead mill type apparatus having a rotating disk and a dispersion medium in a dispersion tank, and the like can be used. Which device is used may be determined in consideration of the viscosity when the carbonaceous material (N) and the organic material are mixed.
[0018]
On the other hand, when a continuous apparatus is used, a pipeline mixer may be used, or a continuous bead mill (medium disperser) may be used. Further, a kneading machine used for ordinary resin processing or the like may be used after taking measures against liquid leakage. When the mixing device and the device in charge of the next process are separate, by using a continuous mixer, the conveyance to the device in charge of the next step can be performed simultaneously with mixing, and the manufacturing process can be made more efficient. .
[0019]
In addition, there is a reaction chamber in which a plurality of puddles or sawtooth paddles fixed to the shaft and a plurality of puddles are arranged with different phases inside, and the inner wall surface is the most effective for rotation of the paddle. If an externally heated reactor with a structure in which a plurality of paddles are arranged in the axial direction of the shaft is formed in a cylindrical shape along the outer line, the mixing process and the intermediate substance are obtained with the same device Process.
B. Process for obtaining intermediate substances (devolatilization / polycondensation reaction process)
The mixture in which the carbonaceous material (N) is sufficiently uniformly dispersed in the mixing step and the organic matter is sufficiently filled in the pores of the carbonaceous material (N) is heated while being kneaded (stirred) in this step, and the carbonaceous material particles (N) and the organic component are highly dispersed, and are recovered as an intermediate product in which a certain volatile component is removed and heat-treated in the organic material.
[0020]
In this step, heating with constant stirring is the most important point. As an apparatus suitable for this process, (a) as shown in FIG. 1, it has a reaction chamber (3) with a paddle (2) rotated by a shaft (1) inside, and the wall surface of the reaction chamber is Formed substantially along the outermost line of the paddle rotation, preferably in a long catamaran shape, the paddles are arranged in pairs in the axial direction of the shaft so as to slidably engage the opposite sides. (B) As shown in FIG. 2, a single shaft (11) and a plurality of pavement or sawtooth paddles (12) fixed to the shaft are arranged inside the paddle with different phases. A reaction chamber (13), the inner wall of which is formed substantially along the outermost line of rotation of the paddle, preferably in a cylindrical shape, and the gap is minimized, and the paddle is the axis of the shaft. A (external heat type) reactor having a structure in which a plurality of sheets are arranged in the direction can be mentioned. By using a reactor having such a structure, a non-aqueous solvent secondary battery negative electrode material having good quality in which the pores of the carbonaceous material particles (N) are also filled with the carbonaceous material (S) is obtained. Can do.
[0021]
Examples of the above-mentioned (a) type reaction apparatus include “KRC reactor” and “SC processor” manufactured by Kurimoto Iron Works, “TEM” manufactured by Toshiba Machine Cellmac Co., Ltd., manufactured by Nippon Steel Works, Ltd. There is “TEX-K”. Examples of the (b) type reaction apparatus include “Leedige Mixer” manufactured by Redige Corporation, “Proshear Mixer” manufactured by Taiheiyo Kiko Co., Ltd., and “DT Dryer” manufactured by Tsukishima Kikai Co., Ltd.
[0022]
Further, in the above-mentioned type (b) apparatus, it is possible to install one or a plurality of screw-type crushing blades (14) rotating at high speed on the wall surface of the reaction chamber in one stage or multiple stages in the mixing operation or the subsequent reaction operation. This is preferable because it is possible to more reliably prevent the occurrence of and to obtain a more uniform intermediate substance.
By using such a reactor,
B) An extremely thin organic material such as the electrode material of the present invention can be uniformly and efficiently attached to the surface of the graphitic carbonaceous material.
B) The heat treatment step that is indispensable for the production of the carbon material, until the organic substance changes to a sufficiently aromatized structure, can be continuously performed.
C) The organic substance can be prevented from sticking to the inner wall of the reaction tank by the stirring blade.
D) The rotation of the crushing blade generates a centrifugal vortex, which enables precise mixing of the raw materials and prevents the occurrence of debris. Thereby, in the mixing step, the carbonaceous material particles and the organic matter are very well dispersed, and in the reaction step, stirring is possible even after the reactant has stopped showing fluidity, and the carbonaceous material particles are uniformly dispersed, It is possible to obtain a uniformly heat-treated product in which the coated carbon is filled into the pores and is not biased depending on the location in the reaction vessel.
E) In particular, when the (b) type reaction apparatus is used, the mixing step and the step of obtaining the intermediate substance can be performed simultaneously.
There are advantages such as.
[0023]
In this step, the atmosphere in the reaction apparatus is preferably an inert atmosphere or a non-oxidizing atmosphere. However, the atmosphere is not particularly limited as long as the intermediate material does not deteriorate due to oxidation. Further, by reducing the pressure in the reaction tank to a reduced pressure state, the defoaming effect from the fine powder can be enhanced, the dispersibility can be improved, and the volatile matter removing effect from the graphitic carbonaceous / organic mixed slurry can be enhanced. Although the optimum conditions for the heat treatment temperature in this step vary depending on the type of organic substance, they are not lower than the boiling point of the solvent and are usually in the range of 50 ° C to 600 ° C, preferably in the range of 50 ° C to 500 ° C.
C. Process for obtaining carbonized substances (carbonization process)
Intermediate substances consisting of carbonaceous particles (N) obtained from the devolatilization / polycondensation process and organic substances that are fully aromatized (carbon precursor) are inert in this process, such as nitrogen gas, carbon dioxide gas, argon gas, etc. Heated under gas flow. In this process, the thermochemical reaction of the carbon precursor proceeds, oxygen, nitrogen and hydrogen remaining in the precursor composition are discharged out of the system, and structural defects are removed depending on the degree of heat treatment, and graphitization. Increase the degree of.
[0024]
The heat history temperature condition is important as the heat treatment condition of this step. The lower limit of the temperature is usually 600 ° C. or higher, preferably 800 ° C. or higher, more preferably 850 ° C. or higher, although it slightly varies depending on the type of heavy oil aromatized and its thermal history. On the other hand, the upper limit temperature can be basically raised to a temperature that does not have a structural order exceeding the crystal structure of the carbonaceous material (N). Therefore, the upper limit temperature of the heat treatment is usually 2500 ° C. or lower, preferably 2000 ° C. or lower, more preferably 1500 ° C. or lower. Under such heat treatment conditions, the heating rate, cooling rate, heat treatment time, etc. can be arbitrarily set according to the purpose. Further, after heat treatment in a relatively low temperature region, the temperature can be raised to a predetermined temperature.
[0025]
In addition, the reactor used for this process may be a batch type or a continuous type, and may be one or more.
D. Powder processing process
In this way, the carbonaceous material (S) is carbonized in the carbonization step, and the product that is complexed in a state where a part or the whole of the carbonaceous material (N) is coated is ground, crushed and classified as necessary in this step. A powder processing treatment such as a treatment is performed to obtain an electrode material for a non-aqueous solvent secondary battery.
[0026]
The powder processing step can be inserted between the devolatilization / polycondensation reaction step and the carbonization step.
(4) Composite carbonaceous material
The composite carbonaceous material of the present invention can take any shape such as granular or fibrous as a whole, but is preferably granular. In the case of granules, the volume average particle size is 1 to 100 μm, preferably 3 to 30 μm, particularly preferably 5 to 25 μm. In the case of a fibrous form, the diameter is preferably 0.5 to 25 μm, preferably 1 to 20 μm, particularly preferably 2 to 10 μm, and the length is preferably 10 mm or less, preferably 5 mm or less.
[0027]
Further, the specific surface area of the composite carbonaceous material according to the present invention measured by using the BET method is preferably 1 to 10 m. ² / G, particularly preferably 2 to 6 m ² / B, and in particular, the BET specific surface area of the composite carbonaceous material produced is not less than 1/4 and not more than 3/4, preferably not more than Those within the range of 3 or more and 2/3 or less are preferable.
[0028]
In addition, the composite carbonaceous material of the present invention preferably has the following spectral characteristics in Raman spectrum analysis using an argon ion laser beam having a wavelength of 5145 Å.
In the present invention, the peak intensity and the spectral intensity integrated value are values according to the following conditions. That is, 1580 ± 100 cm ^-1 Peak P in the wavelength range of _A Strength of I _A , The integral value of the spectral intensity is Y _A 1360 ± 100cm ^-1 Peak P in the wavelength range of _B Strength of I _B , The integral value of the spectral intensity is Y _B And
[0029]
The composite carbonaceous material of the present invention has a peak intensity I of both. _B And I _A Ratio, ie R = I _B / I _A Is larger than the R value of the graphitic carbonaceous material used as the core of the composite carbonaceous material, and preferably less than 0.4. The range of 0.11 to 0.33 is particularly preferable, and the range of 0.12 to 0.28 is more preferable for obtaining good electrical performance. The integral value Y of the spectral intensity _B And Y _A Ratio, ie G = Y _B / Y _A The value is preferably larger than the G value of the graphitic carbonaceous material used as the core of the composite carbonaceous material and less than 0.75. It is particularly preferably 0.26 to 0.74, more preferably 0.3 to 0.68.
[0030]
Incidentally, the R value of the graphite-only electrode material is about 0.1 and the G value is about 0.25, while the R value of the conventional composite carbonaceous material having a clear multiphase is 0.4 or more, G The value was about 0.75.
On the other hand, the composite carbonaceous material of the present invention is an X-ray wide-angle diffraction diffractogram using CuKα rays as a radiation source, and the peak derived from the graphitic carbonaceous material (N) is an apparent single peak on the low-angle side. Shows a diffractogram having a very broad peak derived from the carbonaceous material (S) in a shoulder shape, and there is a large difference in the quantity ratio between the graphitic carbonaceous material (N) and the carbonaceous material (S), Processing tends to prevent accurate separation of the peaks. As a particularly preferred embodiment, it is preferable that the X-ray diffraction pattern does not capture the change in crystal structure with the graphitic carbonaceous material used as the nucleus. That is, it is preferable to have a half-value width substantially equal to that of the graphitic carbonaceous material serving as a nucleus in consideration of measurement errors. This half-value width is measured from a curve smoothed by profile fitting the X-ray diffraction spectrum using the non-target Pearson power function. That is, as a preferred embodiment of the present invention, the half width value is within ± 3σ (σ is the standard deviation when measured 10 times) of the half width value of the graphitic carbonaceous material (N) used as the core. Use.
(5) Secondary battery
The composite carbonaceous material is an electrode material comprising a mixture with a polymer binder, a metal capable of forming an alloy with an active material, or a mixture of an active material and an alloy of the metal in accordance with a known method. The electrode material can be directly molded into the shape of an electrode by a method such as roll molding or compression molding and used as a negative electrode. The configuration of the secondary battery of the present invention includes the negative electrode obtained as described above, a known arbitrary positive electrode, and a known arbitrary separator that is interposed between the positive electrode and the negative electrode and holds an electrolyte, for example, Nonwoven fabrics of polyolefin resins such as polyethylene and polypropylene can be employed. Also, as the electrolyte to be impregnated, any known electrolyte, for example, aprotic organic solvent such as ethylene carbonate, propylene carbonate, 1,3-dioxolane, 1,2-dimethoxyethane, 2-methyltetrahydrofuran, etc. LiClO _Four , LiBF _Four , LiAsF ₆ , LiPF ₆ , LiSO _Three CF _Three , LiN (SO ₂ CF _Three ) ₂ A non-aqueous electrolyte solution having a predetermined concentration in which an electrolyte such as the above is dissolved can be used.
[0031]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
[Example 1]
(1) Mixing process
3 kg of artificial graphite powder (KS-44 manufactured by LONZA: d002 = 0.336m, Lc = 100 nm or more, average volume particle size 19 μm) is charged as a carbonaceous material (N) into a stainless steel tank having an internal volume of 20 liters. (S) 1 kg of ethylene heavy end tar (Mitsubishi Chemical Corporation: viscosity 50 cp at 50 ° C.) obtained at the time of naphtha decomposition is added, and 3.5 kg of hard alkylbenzene (Mitsubishi Chemical Corporation) is added as a diluent. The mixture was stirred with a hand mixer for 20 minutes. Furthermore, when the stainless steel container was bathed in hot water at 80 ° C. and further stirred for 10 minutes in the same manner, it was confirmed from the fluidity of the prepared slurry that the degree of mixing was improved visually. In addition, the viscosity of the obtained slurry was 3210 cp.
(2) Volatilization / polycondensation reaction process
Using a measuring gear pump, the slurry mixture obtained in the mixing step is applied to the device of type (a) described in the above specification schematically shown in FIG. 1, that is, one KRCS1 reactor manufactured by Kurimoto Iron Works. Supplying at 3.2 kg / h, a heat treatment pitching reaction of ethylene heavy end tar was performed. The reactor internal temperature was maintained at 430 ° C., and the degree of vacuum was 87.9 × 10 3 Pa (660 torr). Deaeration and devolatilization were performed, and the light fraction of ethylene heavy end tar and the diluent were removed. The product was collected at 1.5 Kg / h in pellet form from the KRC reactor outlet. Thus, a composite of carbonaceous material particles and heat-treated pitch was obtained. In addition, a total of 15 convex lens type paddles with a diameter of 25 mm were attached to the KRC reactor used for the reaction by shifting 45 degrees.
(3) Carbonization process
The composite particles of the carbonaceous material particles and the sufficiently aromatized pitch were heat-treated in a batch heating furnace. The composite powder was put into an internal heating furnace in a graphite container, and nitrogen gas was heated to 950 ° C. in 3 hours under a flow rate of 5 liters / minute and held for 1 hour. Then, it cooled to room temperature and obtained the composite with which the coating phase was carbonized.
(4) Powder processing process
The composite obtained in the carbonization step was pulverized using an impact pulverizer to obtain a carbon-based composite powder having a certain particle size distribution. In addition, the amount of organic carbides with respect to 100 parts by weight of graphite is shown in the table.
(5) Analysis of carbon composite powder
Analysis was performed according to the following procedure. The results are shown in Table 1.
(5-1) (002) plane spacing (d002), crystallite size Lc
If the carbonaceous material is a powder, it is powdered in an agate mortar as it is in the form of a fine piece, mixed with about 15 wt% of X-ray standard high purity silicon powder, mixed in a sample cell, A wide angle X-ray diffraction curve was measured by a reflective diffractometer method using CuKα rays monochromatized with a graphite monochromator as a radiation source. The obtained X-ray diffraction curve has a shape in which two peaks derived from different crystallinities are overlapped, and the peak derived from the graphitic carbonaceous material is an apparent single peak on the lower angle side. A very broad peak derived from the carbonaceous coating layer appeared in a shoulder shape. However, since there is a difference in the amount ratio between the graphitic carbonaceous material of the composite carbonaceous material and the carbonaceous material adhering to the surface, it was impossible to perform accurate peak separation by statistical treatment.
(5-2) Raman spectrum analysis:
In Raman spectrum analysis using an argon ion laser beam having a wavelength of 514.5 nm, the intensity IA of the peak PA near 1580 cm −1 and the intensity IB of the peak PB in the range of 1360 cm −1 are measured, and the ratio R = IB / IA was measured. The R value of graphite KS-44 was 0.12, and it was judged that the surface was coated.
(5-3) Volume-based average particle diameter
Using a laser diffraction particle size distribution analyzer “LA-700” manufactured by HORIBA, Ltd., volume-based average particle diameter (median diameter) was measured using ethanol as a dispersion medium.
(6) Electrode performance evaluation
(6-1) Preparation of electrode molded body
A toluene solution of a thermoplastic elastomer (styrene / ethylene / butylene / styrene block copolymer) and polyethylene powder were added and stirred to obtain a slurry. The weight ratio was 93% by weight of carbonaceous material, 4% by weight of thermoplastic elastomer (solid content), and 3% by weight of polyethylene powder. This slurry was applied onto a copper foil and pre-dried at 80 ° C. Further, after being crimped to a copper foil, it was punched out on a disk having a diameter of 20 mm and dried under reduced pressure at 110 ° C. to obtain an electrode.
(6-2) Evaluation of wetting
In order to compare the magnitude of wetting with the electrolytic solution, the contact angle of the electrode prepared in (6-1) was measured using a goniometer-type contact angle measuring device. For the measurement, propylene carbonate having a purity of 99.9% was used as a single solvent. The result was not measurable due to the small contact angle. This indicates that the affinity between the solvent and the electrode is very good. The reason for using propylene carbonate is that single ethylene carbonate is solid at room temperature, and in order to make ethylene carbonate liquid, other components must be mixed as a co-solvent, and the experimental conditions cannot be simplified. The experimental conditions should be as simple as possible to compare the contact angles, and propylene carbonate, which is liquid at room temperature, was selected.
(6-3) Electrode evaluation by half-cell
The separator impregnated with the electrolytic solution was sandwiched between the electrodes, a coin-type cell opposed to the lithium metal electrode was created, and a charge / discharge test was performed. As the electrolytic solution, a solution in which lithium perchlorate was dissolved at a ratio of 1.5 mol / liter in a solvent in which ethylene carbonate and diethylene carbonate were mixed at a weight ratio of 1: 1 was used.
[0032]
In the charge / discharge test, the current value was set to 0.2 mA, the battery was charged until the potential difference between both electrodes was 0 V, and the battery was discharged to 1.5 V. The results are shown in Table 2. The irreversible capacity in the table is a value obtained by subtracting the value of the discharge capacity from the charge capacity, and the charge / discharge efficiency is a value obtained by dividing the discharge capacity by the charge capacity.
[Example 2]
The same operation as in Example 1 was performed except that the maximum treatment temperature was set to 1200 ° C. in the carbonization step. In addition, the X-ray diffraction spectrum figure of this composite carbonaceous material is shown in FIG. From this graph, it was found that the half width was 0.223 °. The full width at half maximum of the X-ray diffraction spectrum of the graphitic carbonaceous material serving as the nucleus shown in Comparative Example 4 described later is 0.216 °, and the standard deviation σ of the full width at half maximum is 3.12 × 10. ^-3 Therefore, it is confirmed that the full width at half maximum of the composite carbonaceous material of Example 2 falls within the range of the full width at half maximum ± 3σ of the graphitic carbonaceous material used as the nucleus.
[Example 3]
The same operation as in Example 1 was performed except that the maximum treatment temperature was set to 2000 ° C. in the carbonization step.
[Example 4]
The same operation as in Example 1 was performed except that the maximum treatment temperature was 2400 ° C. in the carbonization step.
[Example 5]
(1) Mixing process
The mixing step and the devolatilization step were carried out using an apparatus described as type (b) in the above description schematically shown in FIG. 2, that is, a Leedige mixer M-20 type (internal volume 20 liters) manufactured by Redige. First, 3 kg of artificial graphite powder (KS-25 manufactured by LONZA) and 1 kg of ethylene heavy end tar (manufactured by Mitsubishi Chemical Co., Ltd .: viscosity 50 cp at 50 ° C.) from the raw material supply port, and toluene as a diluent. 8 kg was charged and the operation was started. The operating conditions were as follows: the rotational speed of the squeeze type stirring blade was 200 rpm, the rotational speed of the crushing blade was 2000 rpm, and the temperature in the apparatus was room temperature. This operation was performed for 10 minutes.
(2) Volatilization process
Warm water was poured into the jacket of the mixer and heated at 100 ° C. Next, the inside of the apparatus is gradually depressurized, and finally the inside is made 13.33 × 103 Pa (100 torr), degassing and devolatilization are advanced, and the light fraction and diluent of ethylene heavy end tar are removed. It was. Thereafter, the temperature was lowered to room temperature, and a composite in which ethylene heavy end tar was adhered and impregnated into artificial graphite powder was obtained in powder form.
(3) Carbonization process and powder processing process
The same operation as in Example 1 was performed except that the maximum treatment temperature was set to 1200 ° C. in the carbonization step.
(4) Analysis and evaluation of carbon composite powder
The same operation as in Example 1 was performed. The evaluation results are shown in Tables 1 and 2.
[Example 6]
In the same manner as in Example 5, a mixing process and a devolatilization process were carried out using a Leedige mixer M-20 type (internal volume 20 liters) manufactured by Redige. First, 3 kg of artificial graphite powder (KS-44 made by LONZA) and 0.6 kg of ethylene heavy end tar (made by Mitsubishi Chemical Co., Ltd .: viscosity 50 cp at 50 ° C.) from the raw material supply port, and toluene as a diluent 3.0 kg was charged. Subsequent operations were the same as those in Example 1.
[Example 7]
In the same manner as in Example 5, a mixing step and a devolatilization step were performed using a Reedige mixer, M-20 type (internal volume: 20 liters) manufactured by Redige. First, 3 kg of artificial graphite powder (KS-44 made by LONZA) and 0.6 kg of ethylene heavy end tar (made by Mitsubishi Chemical Co., Ltd .: viscosity 50 cp at 50 ° C.) from the raw material supply port, and toluene as a diluent 3.0 kg was charged. Subsequent operations were performed in the same manner as in Example 1 except that the maximum treatment temperature was 1200 ° C. in the carbonization step.
[Example 8]
In the same manner as in Example 5, a mixing step and a devolatilization step were performed using a Reedige mixer, M-20 type (internal volume: 20 liters) manufactured by Redige. First, 3 kg of artificial graphite powder (KS-44 made by LONZA) and 0.2 kg of ethylene heavy end tar (made by Mitsubishi Chemical Co., Ltd .: viscosity 50 cp at 50 ° C.) from the raw material supply port, and toluene as a diluent 3.2 kg was charged. Subsequent operations were the same as those in Example 1.
[Example 9]
In the same manner as in Example 5, a mixing step and a devolatilization step were performed using a Reedige mixer, M-20 type (internal volume: 20 liters) manufactured by Redige. First, 3 kg of artificial graphite powder (KS-44 made by LONZA) and 0.2 kg of ethylene heavy end tar (made by Mitsubishi Chemical Co., Ltd .: viscosity 50 cp at 50 ° C.) from the raw material supply port, and toluene as a diluent 3.2 kg was charged. Subsequent operations were performed in the same manner as in Example 1 except that the maximum treatment temperature was 1200 ° C. in the carbonization step.
[Example 10]
(1) Mixing process
In the same manner as in Example 5, a mixing step and a devolatilization step were performed using a Leedige mixer M-20 type (internal volume 20 l).
[0033]
First, 3 kg of artificial graphite powder (KS-44 manufactured by LONZA) and 0.27 kg of coal tar pitch (manufactured by Nippon Steel Chemical Co., Ltd.) and 3.0 kg of pyridine as a diluent solvent were charged from the raw material supply port. Subsequent operations were the same as those in Example 1.
(2) Volatilization / polycondensation reaction process
Next, the inside was replaced with a nitrogen gas atmosphere, and the temperature increase was started. The internal temperature was set to 110 ° C. over 80 minutes, and mixing was further performed for 90 minutes. After that, the inside is gradually depressurized and finally 30.66 × 10 ^Three Pa (230 torr) was set. This took 30 minutes. After recovering the solvent in this way, the internal temperature was gradually lowered, and the contents were recovered in powder form from the outlet. Thus, a composite in which the coal tar pitch component adhered to and impregnated into the graphite powder was obtained.
Subsequent operations were performed in the same manner as in Example 1 except that the maximum treatment temperature was 1200 ° C. in the carbonization step.
[Example 11]
A sample was prepared in the same manner as in Example 1 using FCC decant oil as the cracked petroleum pitch for the organic matter that finally became the carbonaceous matter (S).
[0034]
First, 3 kg of artificial graphite powder (KS-25: d002 = 0.336 m, Lc = 100 nm or more, average volume particle size of 10 μm or more, manufactured by LONZA) as a carbonaceous material (N) is put into a stainless steel tank having an internal volume of 20 liters, 1 kg of FCC decant oil was added as a raw material for the carbonaceous material (S), and hard alkylbenzene was added as a diluting solvent, followed by stirring for 20 minutes with a hand mixer. Further, the stainless steel container was bathed in hot water at 80 ° C. and further stirred for 10 minutes in the same manner.
Thereafter, a carbon-based composite powder was obtained by the same method. Analysis and electrode evaluation were performed in the same manner as in the other examples.
[Example 12]
(1) Mixing process
3 kg of artificial graphite powder (KS-44 manufactured by LONZA: d002 = 0.336m, Lc = 100 nm or more, average volume particle size 19 μm) is charged as a carbonaceous material (N) into a stainless steel tank having an internal volume of 20 liters. Add 1 kg of ethylene heavy end tar (Mitsubishi Chemical Co., Ltd .: Viscosity of 50 cp at 50 ° C.) obtained at the time of naphtha decomposition as (S), and further add 3.0 kg of toluene as a diluent and 20 minutes with a hand mixer Stir. Furthermore, when the stainless steel container was bathed in hot water at 80 ° C. and further stirred for 10 minutes in the same manner, it was confirmed from the fluidity of the prepared slurry that the degree of mixing was improved visually. In addition, the viscosity of the obtained slurry was 3500 cp.
(2) Volatilization / polycondensation reaction process
The slurry mixture obtained in the mixing step is supplied to a SC processor SCP-100 type manufactured by Kurimoto Iron Works Co., Ltd. at 75 Kg / h using a slurry pump for high viscosity, and ethylene heavy end tar and toluene are mixed. Distillation reaction was performed. The reactor internal temperature was maintained at 190 ° C., the degree of vacuum was 87.9 × 10 3 Pa (660 torr), deaeration and devolatilization were performed, and the light fraction of ethylene heavy end tar and the diluent were removed. The product was recovered in pellet form at 36 Kg / h from the KRC reactor outlet. In this way, a composite of carbonaceous particles and ethylene heavy end tar residue was obtained.
[0035]
Subsequent operations were performed in the same manner as in Example 1 except that the maximum treatment temperature was 1200 ° C. in the carbonization step.
[Comparative Example 1]
A composite carbonaceous powder having an excessive amount of organic matter adhering to the graphitic carbonaceous material was prepared in the same manner as in Example 1 and evaluated.
[0036]
First, 3 kg of artificial graphite powder (KS-44: d002 = 0.336 m, Lc = 100 nm or more, average volume particle size 19 μm, manufactured by LONZA) was charged as a carbonaceous material (N) into a stainless steel tank having an internal volume of 20 liters, 7 kg of ethylene heavy end tar (manufactured by Mitsubishi Chemical Co., Ltd .: viscosity 50 cp at 50 ° C.) obtained during naphtha decomposition was added as a raw material for the carbonaceous material (S), and the mixture was stirred with a hand mixer for 20 minutes. Further, the stainless steel container was bathed in hot water at 80 ° C. and further stirred for 10 minutes in the same manner.
(2) Volatilization / polycondensation reaction process
The slurry-like mixture obtained in the mixing step was supplied at 3.1 Kg / h to one KRCS1 reactor manufactured by Kurimoto Iron Works Co., Ltd. using a measuring gear pump, and a heat treatment pitching reaction of ethylene heavy end tar was performed. . The reactor internal temperature was maintained at 430 ° C., the degree of vacuum was 87.9 × 10 3 Pa (660 torr), degassing and devolatilization were performed, and the light fraction of ethylene heavy end tar was removed. The product, which is a semi-solid solution exhibiting high viscosity, was recovered at 1.5 Kg / h in pellet form from the KRC reactor outlet. Thus, a composite of carbonaceous material particles and heat-treated pitch was obtained. In addition, a total of 15 convex lens type paddles with a diameter of 25 mm were attached to the KRC reactor used for the reaction by shifting 45 degrees.
[0037]
Subsequent operations were performed in the same manner as in Example 1 except that the maximum treatment temperature was 1200 ° C. in the carbonization step.
In addition, the X-ray diffraction spectrum figure of this composite carbonaceous material is shown in FIG. From this graph, it was found that the full width at half maximum of the composite carbonaceous material of Comparative Example 1 was 0.230 °. The full width at half maximum of the X-ray diffraction spectrum of the graphitic carbonaceous material serving as the nucleus shown in Comparative Example 4 described later is 0.216 °, and the standard deviation σ of the full width at half maximum is 3.12 × 10. ^-3 Therefore, it is confirmed that the half-value width of the composite carbonaceous material of Comparative Example 1 is outside the range of the half-value width ± 3σ of the graphitic carbonaceous material used as the nucleus.
[Comparative Example 2]
First, 3 kg of artificial graphite powder (KS-44: d002 = 0.336 m, Lc = 100 nm or more, average volume particle size 19 μm, manufactured by LONZA) was charged as a carbonaceous material (N) into a stainless steel tank having an internal volume of 20 liters, Ethylene heavy end tar (manufactured by Mitsubishi Chemical Co., Ltd .: Viscosity 50 cp at 50 ° C.) 4.2 Kg obtained as a raw material for carbonaceous material (S), and hard alkylbenzene (manufactured by Mitsubishi Chemical Corporation) 3 0.0 kg was added and stirred with a hand mixer for 20 minutes. Further, the stainless steel container was bathed in hot water at 80 ° C. and further stirred for 10 minutes in the same manner. Subsequent operations were performed in the same manner as in Example 1 except that the maximum treatment temperature was 1200 ° C. in the carbonization step.
[Comparative Example 3]
A composite carbonaceous powder having an excessive amount of organic substances adhering to the graphitic carbonaceous material was prepared and evaluated in the same manner as in Example 5.
(1) Mixing process
First, 3 kg of artificial graphite powder (KS-44 manufactured by LONZA) and 1.6 kg of coal tar pitch (manufactured by Nippon Steel Chemical Co., Ltd.) and 3 kg of pyridine as a diluting solvent were introduced from the raw material supply port, and the operation was started. . The operating conditions were as follows: the rotational speed of the squeeze type stirring blade was 230 rpm, the rotational speed of the crushing blade was 3000 rpm, and the temperature in the apparatus was 30 ° C.
(2) Volatilization / polycondensation reaction process
Next, the inside was replaced with a nitrogen gas atmosphere, and the temperature increase was started. The internal temperature was set to 110 ° C. over 80 minutes, and mixing was further performed for 90 minutes. After that, the inside is gradually depressurized and finally 30.66 × 10 ^Three Pa (230 torr) was set. This took 40 minutes. After recovering the solvent in this way, the internal temperature was gradually lowered, and the contents were recovered in a granulated state from the outlet. A composite of graphite powder and coal tar pitch could be obtained as a substantially uniform granulated product having a diameter of about 2 mm.
[0038]
Subsequent operations were performed in the same manner as in Example 1 except that the maximum treatment temperature was 1200 ° C. in the carbonization step.
[Comparative Example 4]
A comparative experiment was conducted using artificial graphite KS-44 manufactured by LONZA as artificial graphite powder without surface modification. An X-ray diffraction spectrum of this graphite is shown in FIG. From this graph, it was found that the half width of the graphite of Comparative Example 4 was 0.216 °. The standard deviation σ of the half width is 3.12 × 10 ^-3 °.
[Comparative Example 5]
A comparative experiment was conducted using artificial graphite KS-25 manufactured by LONZA as artificial graphite powder not subjected to surface modification.
[Comparative Example 6]
A comparative experiment was conducted using natural graphite NG-7 manufactured by Kansai Thermal Chemical Co., Ltd. as artificial graphite powder without surface modification.
[0039]
[Table 1]

[0040]
[Table 2]

[0041]
【The invention's effect】
As described above, according to the non-aqueous solvent secondary battery electrode material of the present invention, it is possible to maintain a high discharge capacity comparable to that of graphite, while maintaining a very low irreversible capacity and excellent charging efficiency. It is possible to provide a non-aqueous solvent secondary battery in which characteristics are obtained and stability with respect to an electrolytic solution is improved.
[0042]
Moreover, according to the production method of the present invention, it is possible to stably and efficiently produce such a high-performance and uniform composite carbonaceous material.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a reactor of type (a) used in the present invention.
FIG. 2 is a diagram showing an example of a reactor (b) type used in the present invention.
3 is a graph showing an X-ray diffraction spectrum of graphitic carbonaceous material or graphite used in Example 2, Comparative Example 1 and Comparative Example 4. FIG.
[Explanation of symbols]
1. Shaft, 2. Paddle, 3. Reaction chamber,
11 .... Shaft, 12 .... Paddle, 13 .... Reaction chamber, 14 .... Screw-type crushing blade

Claims (14)

(1) A step of mixing graphitic carbonaceous particles and organic matter to obtain a mixture;
(2) heating the mixture to a temperature of 50 ° C. or higher and lower than 600 ° C. with stirring to obtain an intermediate substance; and (3) heating the intermediate substance to 600 ° C. or higher in an inert gas atmosphere; A composite carbonaceous material obtained by carbonizing and adhering to the surface of a graphitic carbonaceous material an organic carbide that is 12 parts by weight or less and 0.1 parts by weight or more as a residual carbon amount with respect to 100 parts by weight of the graphitic carbonaceous material. The manufacturing method of the electrode material for nonaqueous solvent secondary batteries which consists of a composite carbonaceous material including the process to obtain.   The method for producing an electrode material for a non-aqueous solvent secondary battery according to claim 1, wherein in the step (1), the mixture further contains a solvent.   The manufacturing method of the electrode material for nonaqueous solvent secondary batteries of Claim 2 whose solvent is a solvent which consists of an aromatic organic solvent or a heterocyclic compound.   The manufacturing method of the electrode material for nonaqueous solvent secondary batteries of any one of Claims 1-3 which performs a process (1) and a process (2) simultaneously.   The manufacturing method of the electrode material for nonaqueous solvent secondary batteries of any one of Claims 1-3 which performs a process (2) after a process (1).   The nonaqueous solvent secondary battery according to claim 5, wherein in step (1), a mixture that is a slurry-like body having a viscosity adjusted to 10,000 cp or less is obtained, and the mixture that is the slurry-like body is subjected to step (2). Manufacturing method of electrode material. In the step (2), the mixture has a reaction chamber having a paddle rotated by a shaft therein, and the inner wall surface of the reaction chamber is formed substantially along the outermost line of rotation of the paddle, and the volatile component is introduced into mixing and stirring apparatus having a mechanism for degassed, with stirring 50 ° C. or higher, and heating to a temperature below 600 ° C., to obtain a solid intermediate material, according to claim 1～3,5,6 The manufacturing method of the electrode material for nonaqueous solvent secondary batteries of any one of these.   The manufacturing method of the electrode material for nonaqueous solvent secondary batteries of any one of Claims 1-7 whose organic substance is heavy oil in a process (1). The electrode material for nonaqueous solvent secondary batteries manufactured by the manufacturing method of the nonaqueous solvent secondary battery electrode material of any one of Claims 1-8. Intensity I _B ratio of the intensity I _A and 1360 peak P _B in the range of ± 100 cm ^-1 peak P _A in the range of 1580 ± 100 cm ^-1 in the Raman spectrum analysis of a composite carbonaceous material, R = I _B / I _A is The electrode material for a non-aqueous solvent secondary battery according to claim 9, which is larger than the R value of the graphitic carbonaceous material used for the composite carbonaceous material and less than 0.4.   The non-aqueous solution according to claim 9 or 10, wherein the half width in the X-ray diffraction pattern of the composite carbonaceous material is within ± 3σ (σ is a standard deviation) of the half width in the X-ray diffraction diagram of the graphitic carbonaceous material used for the core. Electrode material for solvent secondary battery.   The electrode material for a non-aqueous solvent secondary battery according to any one of claims 9 to 11, wherein a distance (002) between (002) planes of the graphitic carbonaceous material is 0.345 nm or less.   The electrode material for a nonaqueous solvent secondary battery according to any one of claims 9 to 12, wherein the size Lc of the crystallite in the c-axis direction of the graphitic carbonaceous material is 15 nm or more.   14. The non-aqueous solvent secondary battery according to claim 9, wherein the non-aqueous solvent secondary battery includes a positive electrode, a negative electrode, and an electrolyte solution in which an electrolyte is dissolved in a non-aqueous solvent. Nonaqueous solvent secondary battery using battery electrode material.

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