JP2004107095A - Method for manufacturing lithium transition metal compound oxide - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a lithium transition metal compound oxide in which the content of iron powder or the like is reduced as much as possible. <P>SOLUTION: In the method for manufacturing the lithium transition metal compound oxide by pulverizing aqueous slurry containing at least one kind of compound of Mn, Co and Ni and a lithium compound in a wet pulverizing machine, spray drying and firing, iron powder or the like is removed by attracting with magnetic force from the aqueous slurry or the source compound used for the preparation of the aqueous slurry in the processes prior to spray drying. <P>COPYRIGHT: (C)2004,JPO

Description

【００１７】
磁力磁選機の磁気マトリックスの磁束密度は、鉄粉を除去するためには１００ガウス以上、特に２００ガウス以上とするのが好ましい。ステンレス鋼粉も除去するには４００ガウス以上、特に７００ガウス以上とするのが好ましい。鉄粉などを十分に除去し、かつ他の金属化合物を吸着させないためには、磁気マトリックスの磁束密度は１０００ガウス以上で、上限は水性スラリー内に含有されている金属化合物が吸着される磁束密度未満、特に金属化合物が吸着される磁束密度よりも１００ガウス以上低い磁束密度とするのが好ましい。
【００１８】
本発明の好ましい一態様では、粉砕工程中に湿式粉砕機から水性スラリーの一部を抜出し、これを磁力による磁性粉の除去装置を通過させたのち湿式粉砕機に戻すことにより磁性粉の除去を行う。一般に水性スラリーは湿式粉砕中に摩擦熱により高温となり、これに伴って粘度が上昇する。従って湿式粉砕に際しては、湿式粉砕機から水性スラリーの一部を抜出し、これを冷却コイルや冷却ジャケットなどを備えた貯槽を経由して湿式粉砕機に戻す循環操作を行うことにより、湿式粉砕機の水性スラリーの温度を２０〜５０℃、特に２５〜４０℃に制御するのが好ましい。水性スラリーの温度は、貯槽の冷却コイルや冷却ジャケットに供給する冷却水の温度や水量を制御することにより容易に調節できる。各期間などで周囲の温度が低い場合には、循環速度の如何によっては循環路からの自然放熱により、冷却水で冷却しなくても上記の温度範囲に維持することが可能な場合もある。この水性スラリーの冷却のための循環路に磁性粉の除去装置を設置すると、水性スラリーの冷却と、水性スラリーからの鉄粉などの除去とを同時に行うことができる。すなわちこの方法によれば、湿式粉砕機から発生したステンレス鋼粉や、粉砕に伴い原料の金属化合物の粒子から放出された鉄粉などは、水性スラリーの循環に伴って逐次磁性粉の除去装置で除去されていくので、粉砕終了後に改めて水性スラリーを磁性粉の除去装置に通過させて鉄粉などを除去する必要が無い。なお、粉砕中に湿式粉砕機から水性スラリーの一部を抜出して磁性粉の除去装置を通過させる場合には、前述の通過回数は下記式で算出する。
【００１９】
【数１】
通過回数＝除去装置を通過した水性スラリー量／湿式粉砕系内の水性スラリー
量
【００２０】
湿式粉砕機で所望の平均粒子径にまで粉砕した水性スラリーは、噴霧乾燥して粉体とするのが好ましい。噴霧乾燥は水性スラリーの粘度が５０ｍＰａ・Ｓ以上かつ３０００ｍＰａ・Ｓ以下で行うのが好ましい。粘度がこれより小さいと生成する粉体の粒径が小さくなりすぎたり、粉体が破損しやすくなったりする。また、粘度がこれよりも大きいと水性スラリーの取扱いが困難となる。水性スラリーの粘度の下限は１００ｍＰａ・Ｓ以上、特に２００ｍＰａ・Ｓ以上であるのが好ましく、また上限は２０００ｍＰａ・Ｓ以下、特に１６００ｍＰａ・Ｓ以下であるのが好ましい。なお、水性スラリーの粘度はＢＭ型粘度計を用いて行う。すなわち室温において粘度計のローターを水性スラリー中で回転させ、その回転軸にかかる抵抗力（捻れの力）から粘度を算出する。
【００２１】
水性スラリーの噴霧乾燥そのものは常法に従って行えばよい。例えばノズルから高速で噴出する気流中に水性スラリーを供給して、液滴として飛散・乾燥させる方法を採用することができる。気流としては通常は空気流を用い、１００ｍ／秒以上で噴出させる。噴出速度が小さいと適切な液滴の形成が困難である。気流の噴出速度は２００ｍ／秒以上、特に３００ｍ／秒以上であるのが好ましい。またその上限は通常は１０００ｍ／秒以下である。ノズルとしては例えば特許第２７９７０８０号に記載されているものを用いればよい。好ましくは図２に示すような四流体ノズルを用いる。噴霧乾燥は生成する粉体の平均粒子径が５０μｍ以下、特に３０μｍ以下となるように行うのが好ましい。しかし平均粒子径があまり小さいものは製造が困難であり、かつ粒子径が小さいことに伴う利点もないので、平均粒子径は４μｍ以上、特に５μｍ以上となるように噴霧乾燥を行うのが好ましい。なお、噴霧乾燥機に導入する乾燥ガスの温度は通常は下限が５０℃以上、好ましくは７０℃以上であり、上限は１２０℃以下、好ましくは１００℃以下である。乾燥ガスの温度が低過ぎると、噴霧乾燥機内部で結露が生じて、粉体が固着したり閉塞が生じたりする。また温度が高過ぎると得られる粉体に中空のものが多くなり、粉体の充填密度が低下するようになる。
【００２２】
噴霧乾燥により得た粉体は、次いで焼成してリチウム遷移金属複合酸化物に転換する。水性スラリー中にリチウム化合物を含有させなかったり、少量しか含有させなかった場合には、噴霧乾燥により得た粉体にリチウム化合物の粉体を配合し、よく混合して均一組成として焼成する。リチウム化合物としては、前述したものを用いればよい。リチウム化合物は平均粒子径で５００μｍ以下、好ましくは１００μｍ以下に粉砕して用いる。平均粒子径が小さいほど遷移金属化合物との均一混合が容易であり、また焼成に際しての反応も良好に進行する。従ってリチウム化合物はできるだけ小粒径に粉砕するのが好ましく、５０μｍ以下、更には２０μｍ以下に粉砕するのが好ましい。最も好ましいのは５μｍ以下に粉砕することである。しかし粒径が小さくなるほど粉砕に伴う効果は漸減し、かつ粉砕費用も嵩むので、０．０１μｍよりも小さくするのは有利ではない。通常は０．１μｍ以上、特に０．２μｍ以上となるように粉砕する。費用と効果の点よりして０．５μｍ以上となるように粉砕するのが最も好ましい。焼成は常法に従って行えばよい。焼成装置としては箱型炉、管状炉、トンネル炉、ロータリーキルンなど常用の焼成装置を用いることができる。また焼成温度などは、目的とするリチウム遷移金属複合酸化物に応じて適宜選択すればよい。例えば遷移金属がマンガンの場合には、酸素雰囲気下６００〜９００℃で焼成したのち、５００℃以下まで１０℃／分以下の速度で徐冷する方法や、６００〜９００℃で空気又は酸素雰囲気下で焼成したのち、４００℃程度の温度で酸素雰囲気下に焼鈍する方法などが挙げられる。焼成方法については特開平９−２５９８８０、３０６４９０、３０６４９３号公報などに詳しく説明されている。生成するリチウムマンガン複合酸化物は、ＬｉＭｎ_２Ｏ_４を基本組成とするスピネル構造のマンガン酸リチウム、又はＬｉＭｎＯ_２を基本組成とする層状構造のマンガン酸リチウムであるが、スピネル型のものの方が製造が容易であり、かつ正極活物質として用いた場合のサイクル特性も優れているので好ましい。
焼成により生成するスピネル構造のリチウムマンガン複合酸化物の好ましい組成の一つは下記式で表される。
【００２３】
【数２】
Ｌｉ_ｂＭｎ_２−ａＭａＯ_４
【００２４】
（ＭはＢ、Ａｌ、Ｓｎ、Ｃｕ、Ｔｉ、Ｚｎ、Ｃｏ及びＮｉよりなる群から選ばれる少なくとも１種であり、０＜ｂ≦１．５、０＜ａ≦１）
なかでも好ましいのは下記式で表されるものである。
【００２５】
【数３】
Ｌｉ_ＹＭｎ_２−ｘＡｌ_ｘＯ_４
【００２６】
（０＜Ｘ≦１．０、０．９≦Ｙ≦１．１）
なお、上記のいずれの式においても酸素の量は変動し得る。
遷移金属がニッケルやコバルトである場合には、空気又は酸素雰囲気中で７００℃ないし１０５０℃で焼成すればよい。焼成温度の下限は７２５℃、特に７５０℃であるのが好ましく、また上限は１０００℃以下、特に９５０℃以下であるのが好ましい。最も好ましい焼成温度は８００〜９００℃である。また結晶欠陥が少ないリチウム遷移金属複合酸化物を得るには、焼成後は徐冷、例えば５℃／分以下の速度で徐冷するのが好ましい。焼成時間は上記の温度で通常は３０分間以上であればよく、長くても５０時間以下で十分である。なお、焼成時間が長すぎると後の工程で解砕が困難になることがあるので、２５時間以下、特に２０時間以下であるのが好ましい。一般に最も好ましい焼成時間は７〜１５時間である。焼成により生成するリチウムニッケル複合酸化物の好ましい組成の一つは下記式で表される。
【００２７】
【数４】
Ｌｉ_ＸＮｉ_ＹＱ_{（１−Ｙ）}Ｏ_２
【００２８】
（ＱはＣｏ、Ａｌ、Ｍｇ、Ｇａ、Ｔｉ及びＣａよりなる群から選ばれる少なくとも１種であり、０＜Ｘ≦１．２、０．５≦Ｙ＜１．０）
なかでも好ましいのは下記式で表されるものである。
【００２９】
【数５】
Ｌｉ_ＸＮｉ_ＹＣｏ_ＺＱ′_{（１−Ｙ−Ｚ）}Ｏ_２
【００３０】
（Ｑ′はＣｏ、Ａｌ、Ｍｇ、Ｇａ、Ｔｉ及びＣａよりなる群から選ばれる少なくとも１種であり、０＜Ｘ≦１．２、０．５≦Ｙ＜１．０、０＜Ｚ≦０．５）
また、遷移金属としてニッケルとマンガンを併用する場合には、下記式で表されるものであるのが好ましい。
【００３１】
【数６】
Ｌｉ_ＸＮｉ_ＹＭｎ_ＺＱ_{（１−Ｙ−Ｚ）}Ｏ_２
【００３２】
（ＱはＣｏ、Ａｌ、Ｍｇ、Ｇａ、Ｔｉ及びＣａよりなる群から選ばれた少なくとも１種であり、０＜Ｘ≦１．２、１≦Ｙ／Ｚ≦９、０＜（１−Ｙ−Ｚ）≦０．５）
また、焼成により生成するリチウムコバルト遷移金属複合酸化物の好ましい組成の一つは下記式で表される。
【００３３】
【数７】
Ｌｉ_ＸＣｏ_１−ＹＡ_ＹＯ_２
【００３４】
（ＡはＢ、Ｍｇ、Ｓｉ、Ｃｕ、Ｔｉ、Ｖ、Ｍｎ、Ｎｉ、Ｓｎ、Ｚｒ、Ｓｂ、Ｎｂ、Ｒｕ、Ｐｂ、Ｈｆ及びＴａよりなる群から選ばれた少なくとも１種を表し、０＜Ｘ≦１．２、０≦Ｙ≦０．２５）
焼成により得られたリチウム遷移金属複合酸化物は解砕して、正極活物質とする。解砕はボールミル、ジェットミル、ピンミルなどを用いて、平均粒子径が１００μｍ以下、好ましくは５０μｍ以下となるように行う。解砕したリチウム遷移金属複合酸化物はそのまま正極活物質として用いることもできるが、分級して大粒径のものを除去するのが好ましい。通常は重力、慣性力、遠心力などを用いる気流分級機により、粒径が１００μｍ以下、特に５０μｍ以下のものを取得するのが好ましい。また、これらの解砕や分級工程においても装置から鉄粉などが混入することがあるので、これらの工程の後で再び磁力による鉄粉などの除去を行うのが好ましい。除去装置としては水性スラリー中の鉄粉などの除去に用いたものと同様のものを用いればよい。
【００３５】
なお、本明細書において、スラリー中の固形分の平均粒子径、噴霧乾燥後の粉体の平均粒子径、及びリチウム遷移金属複合酸化物の平均粒子径は、公知のレーザー回折／散乱式粒度分布測定装置によって測定する。この方法ではスラリー又は粉体を分散媒に分散させ、この試料溶液にレーザー光を照射し、粒子に入射されて散乱（回折）した散乱光をディテクタで検出する。検出された散乱光の散乱角θ（入射方向と散乱方向の角度）は、大きい粒子の場合は前方散乱（０＜θ＜９０゜）となり、小さい粒子の場合は側方散乱又は後方散乱（９０゜＜θ＜１８０゜）となる。測定された角度分布値から、入射光波長及び粒子の屈折率等の情報を用いて粒子径分布を算出する。更に得られた粒子径分布から平均粒子径を算出する。測定の際に用いる分散媒としては、例えば０．１重量％ヘキサメタリン酸ナトリウム水溶液を挙げることができる。
【００３６】
本発明で得られるリチウム遷移金属複合酸化物はリチウム二次電池の正極の活物質として用いるのに好適である。
正極は、通常は上記の正極活物質と結着剤と導電剤とを含有するスラリーを集電体上に塗布・乾燥することで形成することができる。塗布・乾燥により形成される活物質層中の正極活物質の割合は、通常１０重量％以上、好ましくは３０重量％以上、さらに好ましくは５０重量％以上であり、通常９９．９重量％以下、好ましくは９９重量％以下である。正極活物質が多すぎると正極の強度が不足する傾向にあり、少なすぎると容量の面で不十分となる。
【００３７】
導電剤としては、天然黒鉛、人造黒鉛、アセチレンブラックなどのカーボンブラック、ニードルコークス等の無定形炭素等を用いることができる。活物質層中の導電剤の割合は、通常０．０１重量％以上、好ましくは０．１重量％以上、さらに好ましくは１重量％以上であり、通常５０重量％以下、好ましくは２０重量％以下、さらに好ましくは１０重量％以下である。導電剤が多すぎると容量の面で不十分となり、少なすぎると電気導電性が不十分になる。
【００３８】
また、結着剤としては、ポリフッ化ビニリデン、ポリテトラフルオロエチレン、フッ素化ポリフッ化ビニリデン、フッ素ゴム等のフッ素系高分子の外、ＥＰＤＭ（エチレン−プロピレン−ジエン三元共重合体）、ＳＢＲ（スチレン−ブタジエンゴム）、ＮＢＲ（アクリロニトリル−ブタジエンゴム）、ポリ酢酸ビニル、ポリメチルメタクリレート、ポリエチレン、ニトロセルロース等を用いることができる。活物質層中の結着剤の割合は、通常０．１重量％以上、好ましくは１重量％以上、さらに好ましくは５重量％以上であり、通常８０重量％以下、好ましくは６０重量％以下、さらに好ましくは４０重量％以下である。多すぎると容量の面で不十分となり、少なすぎると強度が不十分になる。
【００３９】
また、スラリーを調製する際に使用する溶媒としては、通常は結着剤を溶解あるいは分散する有機溶剤が使用される。例えば、Ｎ−メチルピロリドン、ジメチルホルムアミド、ジメチルアセトアミド、メチルエチルケトン、シクロヘキサノン、酢酸メチル、アクリル酸メチル、ジエチルトリアミン、Ｎ，Ｎ−ジメチルアミノプロピルアミン、エチレンオキシド、テトラヒドロフラン等を用いることができる。また、水に分散剤、増粘剤等を加えてＳＢＲ等のラテックスでスラリー化する場合もある。
【００４０】
活物質層の厚さは、通常１０〜２００μｍ程度である。
集電体としては、アルミニウム、ステンレス鋼、ニッケルメッキ鋼等の金属が用いられ、好ましくはアルミニウムである。
なお、塗布・乾燥によって得られた活物質層は、電極材料の充填密度を上げるためローラープレス等により圧密化するのが好ましい。
【００４１】
本発明の非水系リチウム二次電池に使用する負極活物質としては、炭素材料が好ましい。このような炭素材料としては、天然ないし人造の黒鉛、石油系コークス、石炭系コークス、石油系ピッチの炭化物、石炭系ピッチの炭化物、フェノール樹脂・結晶セルロース等樹脂の炭化物およびこれらを一部炭化した炭素材、ファーネスブラック、アセチレンブラック、ピッチ系炭素繊維、ＰＡＮ系炭素繊維、あるいはこれらの２種以上の混合物等が挙げられる。負極活物質は、通常、結着剤及び必要に応じて導電剤とともにスラリーとし、集電体上に塗布・乾燥して負極とする。リチウム金属そのものや、リチウムアルミニウム合金等のリチウム合金を負極として用いることもできる。負極に使用する結着剤や導電剤としては、正極に使用するものと同様のものを用いればよい。
【００４２】
負極の活物質の厚さは、通常１０〜２００μｍ程度である。
負極の集電体としては、通常は銅、ニッケル、ステンレス鋼、ニッケルメッキ鋼等の金属が用いられ、好ましくは銅である。
非水系電解液としては、各種の電解塩を非水系溶媒に溶解したものを用いることができる。
非水系溶媒としては、例えばカーボネート類、エーテル類、ケトン類、スルホラン系化合物、ラクトン類、ニトリル類、ハロゲン化炭化水素類、アミン類、エステル類、アミド類、燐酸エステル化合物等を使用することができる。これらの代表的なものとしては、プロピレンカーボネート、エチレンカーボネート、クロロエチレンカーボネート、トリフルオロプロピレンカーボネート、ブチレンカーボネート、ジエチルカーボネート、ジメチルカーボネート、エチルメチルカーボネート、ビニレンカーボネート、テトラヒドロフラン、２−メチルテトラヒドロフラン、１，４−ジオキサン、４−メチル−２−ペンタノン、１，２−ジメトキシエタン、１，２−ジエトキシエタン、γ−ブチロラクトン、１，３−ジオキソラン、４−メチル−１，３−ジオキソラン、ジエチルエーテル、スルホラン、メチルスルホラン、アセトニトリル、プロピオニトリル、ベンゾニトリル、ブチロニトリル、バレロニトリル、１，２−ジクロロエタン、ジメチルホルムアミド、ジメチルスルホキシド、燐酸トリメチル、燐酸トリエチル等を挙げることができ、これらを単独又は二種類以上の混合溶媒として用いればよい。
【００４３】
上述の非水系溶媒の中でも、電解質を解離させるために高誘電率溶媒を使用するのが好ましい。高誘電率溶媒とは、概ね２５℃における比誘電率が２０以上の化合物を意味する。高誘電率溶媒のなかでも、エチレンカーボネート、プロピレンカーボネート及びそれらの水素原子をハロゲン等の他の元素またはアルキル基等で置換した化合物を電解液中に含有させるのが好ましい。高誘電率溶媒の電解液中に占める割合は、通常２０重量％以上、好ましくは３０重量％以上、さらに好ましくは４０重量％以上である。該高誘電率溶媒の含有量が少ないと、所望の電池特性が得られない場合がある。
【００４４】
電解塩としては、従来公知のいずれもが使用でき、ＬｉＣｌＯ_４、ＬｉＡｓＦ_６、ＬｉＰＦ_６、ＬｉＢＦ_４、ＬｉＢ（Ｃ_６Ｈ_５）_４、ＬｉＣｌ、ＬｉＢｒ、ＬｉＣＨ_３ＳＯ_３、ＬｉＣＦ_３ＳＯ_３、ＬｉＮ（ＳＯ_２ＣＦ_３）_２、ＬｉＮ（ＳＯ_２Ｃ_２Ｆ_５）_２、ＬｉＣ（ＳＯ_２ＣＦ_３）_３、ＬｉＮ（ＳＯ_３ＣＦ_３）_２等のリチウム塩が用いられる。
【００４５】
また、ＣＯ_２、Ｎ_２Ｏ、ＣＯ、ＳＯ_２等のガスやポリサルファイドＳｘ^２−、ビニレンカーボネート、カテコールカーボネートなど負極表面にリチウムイオンの効率よい充放電を可能にする良好な皮膜を生成する添加剤を任意の割合で電解液中に存在させてもよい。
なお、電解液の代わりに、リチウムイオン等のアルカリ金属カチオンの導電体である高分子固体電解質を用いることもできる。また、上記電解液を、高分子によって非流動化した半固体状電解質を用いることもできる。リチウム二次電池においては、正極と負極との間に、上記のような様々な材料によって電解質層を設けることができる。
【００４６】
正極と負極との間には、通常セパレータが設けられる。セパレータとしては、微多孔性の高分子フィルムが用いられ、その材質としては、ナイロン、ポリエステル、セルロースアセテート、ニトロセルロース、ポリスルホン、ポリアクリロニトリル、ポリフッ化ビニリデン、テトラフルオロエチレンや、ポリプロピレン、ポリエチレン、ポリブテン等のポリオレフィン系高分子を挙げることができる。また、ガラス繊維等の不織布フィルター、さらにはガラス繊維と高分子繊維の複合不織布フィルター等も用いることができる。セパレータの化学的及び電気化学安全性は重要な因子であり、この点から材質としては、ポリオレフィン系高分子が好ましく、特に、電池セパレータの目的の一つである自己閉塞温度の点からポリエチレン製であることが好ましい。
【００４７】
ポリエチレン製セパレータの場合、高温形状維持性の点から超高分子量ポリエチレンであることが好ましく、その分子量の下限は好ましくは５０万、更に好ましくは１００万、最も好ましくは１５０万である。他方分子量の上限は、好ましくは５００万、更に好ましくは４００万、最も好ましくは３００万である。分子量が大きすぎると、流動性が低すぎて加熱されたときにセパレータの孔が閉塞しない場合があるからである。
【００４８】
【実施例】
以下実施例により本発明をより詳細に説明する。なお、ＳＵＳはステンレス鋼を示す。
実施例１
Ｍｎ_２Ｏ_３　１０ｇに対し、粒径１００μｍ程度の鉄粉１ｇを混合したものを試料とした。この試料を紙上に拡げ、磁束密度が６０００ガウスの磁石を、試料が受ける磁力が２０００ガウスになるまで上から近づけた。この状態で紙を５分間左右に揺らした。その結果、鉄粉１ｇが磁石により回収された。
【００４９】
実施例２
鉄粉の代わりに、粒径１００μｍ程度のＳＵＳ粉（未焼成）１ｇを混合したものを試料とした以外は、実施例１と同様にして磁石による磁性粉の回収を行った。その結果、ＳＵＳ粉（未焼成）１ｇが回収された。
実施例３
鉄粉の代わりに、粒径１００μｍ程度のＳＵＳ粉（焼成）１ｇを混合したものを試料とした以外は、実施例１と同様にして磁石による磁性粉の回収を行った。その結果、ＳＵＳ粉（焼成）１ｇが回収された。
【００５０】
実施例４
磁石を試料が受ける磁力が５００ガウスとなるまで近づけた以外は、実施例１と同様にして磁石による磁性粉の回収を行った。鉄粉１ｇが回収された。
実施例５
Ｍｎ_２Ｏ_３　１０ｇの代わりに、Ｎｉ（ＯＨ）_２　１０ｇを用いたものを試料とし、磁石を試料が受ける磁力が２５００ガウスになるまで近づけた以外は、実施例２と同様にして磁石による磁性粉の回収を行った。その結果、ＳＵＳ粉（未焼成）１ｇが回収された。
【００５１】
実施例６
Ｍｎ_２Ｏ_３　１０ｇの代わりに、Ｃｏ（ＯＨ）_２　１０ｇを用いたものを試料とし、磁石を試料が受ける磁力が２０００ガウスになるまで近づけた以外は、実施例２と同様にして磁石による磁性粉の回収を行った。その結果、ＳＵＳ粉（未焼成）１ｇが回収された。
実施例７
Ｍｎ_２Ｏ_３、ＡｌＯＯＨ、ＬｉＯＨ・Ｈ_２Ｏを、それぞれ最終的なスピネル型リチウムマンガン複合酸化物の組成で、Ｌｉ：Ｍｎ：Ａｌ＝１．０４：１．８４：０．１２（原子比）となるように混合したもの１０ｇに、粒径１００μｍ程度の鉄粉１ｇを混合したものを試料とした。この試料を紙上に拡げ、磁束密度が６０００ガウスの磁石を、試料が受ける磁力が２０００ガウスになるまで上から近づけた。この状態で紙を５分間左右に揺らした。その結果、鉄粉１ｇが磁石により回収された。
【００５２】
実施例８
Ｍｎ_２Ｏ_３、ＡｌＯＯＨ、ＬｉＯＨ・Ｈ_２Ｏを、それぞれ最終的なスピネル型リチウムマンガン複合酸化物の組成で、Ｌｉ：Ｍｎ：Ａｌ＝１．０４：１．８４：０．１２（原子比）となるように混合したものに純水を加えて、固形分濃度３０重量％のスラリーを調製した。得られたスラリーを循環式媒体撹拌型湿式粉砕器にかけ、スラリー中の固形分の平均粒子径が０．３μｍになる迄粉砕した。粉砕後のスラリー４０ｍｌと粒径１００μｍ程度の鉄粉１ｇを５０ｍｌビーカーに入れ撹拌した後、５０ｍｍ×１０ｍｍ×１０ｍｍで磁束密度が２２００ガウスのアルニコ磁石で５分間撹拌した。その結果、鉄粉１ｇが磁石により回収された。この操作を繰り返し、鉄粉を回収した後のスラリー１リットルを作成した。このスラリーを液滴微細化機構を有するノズルを設けたスプレードライヤー（藤崎電機株式会社製、マイクロミストドライヤーＭＤＰ−０５０、ノズルタイプはサークルエッジノズル、乾燥塔寸法は２５００ｍｍφ×４８００ｍｍＨ）を用いて、噴霧乾燥を行った。
【００５３】
乾燥塔への乾燥ガス導入量は２３ｍ^３／分、乾燥ガス入口温度は９０℃とした。また、噴霧ノズルとしては、直径３０ｍｍφで、３６０°（環状）方向に水平噴霧可能な型式のものを使用し、ノズルのスラリー出口クリアランスを６００μｍ、スラリーを微細化する為の加圧気体流出口のクリアランスを３５０μｍに設定した。スラリー供給速度は、５６０ｇ／分、加圧気体流の供給速度は１２００Ｌ／分とした（気体流のガス線速は３３０ｍ／秒）。排気ガス温度は４５℃であった。
噴霧乾燥により得た粒子を９００℃で１０時間焼成し、リチウムマンガン複合酸化物を得た。この複合酸化物をボールミルで５分間解砕した。その結果、平均粒子径９μｍのほぼ球状の粒子が得られた。Ｘ線回折したところ、立方晶のスピネル型リチウムマンガン複合化合物の構造を有していることが確認された。
【００５４】
実施例９
Ｍｎ_２Ｏ_３　１０ｇの代わりに、Ｌｉ_１．０４Ｍｎ_１．８４Ａｌ_０．１２Ｏ_４　１０ｇを用いたものを試料とし、磁石を試料が受ける磁力が２５００ガウスになるまで近づけた以外は、実施例２と同様にして磁性粉の回収を行った。その結果、ＳＵＳ粉（未焼成）１ｇが回収された。
【００５５】
実施例１０
Ｍｎ_２Ｏ_３　１０ｇの代わりに、Ｌｉ_１．０４Ｎｉ_０．８Ｃｏ_０．１５Ａｌ_０．０５Ｏ_２　１０ｇを用いたものを試料とし、磁石を試料が受ける磁力が４０００ガウスになるまで近づけた以外は、実施例２と同様にして磁性粉の回収を行った。その結果、ＳＵＳ粉（未焼成）１ｇが回収された。
【００５６】
実施例１２
Ｍｎ_２Ｏ_３　１０ｇの代わりに、ＬｉＣｏＯ_２　１０ｇを用いたものを試料とし、磁石を試料が受ける磁力が５０００ガウスになるまで近づけた以外は、実施例２と同様にして磁性粉の回収を行った。その結果、ＳＵＳ粉（未焼成）１ｇが回収された。
【００５７】
実施例１３
Ｍｎ_２Ｏ_３、ＡｌＯＯＨ、ＬｉＯＨ・Ｈ_２Ｏを、それぞれ最終的なスピネル型リチウムマンガン複合酸化物の組成で、Ｌｉ：Ｍｎ：Ａｌ＝１．０４：１．８４：０．１２（原子比）となるように混合したもの７９２ｇと、粒子径２〜１０μｍのＳＵＳ粉（未焼成）８ｇとを、脱塩水３２００ｇに混合して固形分濃度２０重量％の水性スラリーを調製した。この水性スラリーを長さが０．５ｍで、かつ磁束密度が２０００ガウスのマトリックスを有する日本エリーズマグネチックス（株）社製Ｌ−４湿式高磁力磁選機に０．３ｍ／秒の速度で３回通過させた。その結果を図１に示す。
【００５８】
縦軸のＳＵＳ粉除去率とは、上記水性スラリーを高磁力磁選機に通過させることにより回収されたＳＵＳ粉の重量の、水性スラリーに含まれていたＳＵＳ粉の重量８ｇに対する百分率である。
測定の方法は、まず、マトリックスの付着物を水洗して回収し、その回収物を乾燥機で乾燥し粉末を得た。この粉末を塩酸で溶解してから、ＩＣＰ分光分析により、粉末中の鉄元素の重量を測定した。あらかじめ、水性スラリーの調整に使用したＳＵＳ粉の鉄元素の含有割合をＩＣＰ分光分析で測定した値と、上記で測定した鉄元素の重量とから、マトリックスに付着したＳＵＳ粉の重量を算出した。
【００５９】
実施例１４
Ｍｎ_２Ｏ_３、ＡｌＯＯＨ、ＬｉＯＨ・Ｈ_２Ｏを、それぞれ最終的なスピネル型リチウムマンガン複合酸化物の組成で、Ｌｉ：Ｍｎ：Ａｌ＝１．０４：１．８４：０．１２（原子比）となるように混合したもの７９２ｇと、粒子径２〜１０μｍのＳＵＳ粉（未焼成）８ｇと脱塩水３２００ｇとを混合槽に供給して混合し、水性スラリーとした。この水性スラリーを混合槽から湿式粉砕機に供給して平均粒子径が０．３μｍになるまで粉砕した。粉砕中に水性スラリーの一部を抜出して、マトリックスの磁束密度が２０００ガウスの日本エリーズマグネチックス（株）社製Ｌ−４湿式高磁力磁選機を０．３ｍ／秒で通過させたのち混合槽を経由して湿式粉砕機に戻した。粉砕機内の水性スラリーの温度は２９〜３４℃に保たれていた。水性スラリーを磁選機に１０回通過させたところ、ＳＵＳ粉８ｇが湿式磁選機のマトリックスにより回収された。
【００６０】
粉砕した水性スラリーは、次いで液滴微細化機構を有するノズルを設けたスプレードライヤー（藤崎電機株式会社製、マイクロミストドライヤーＭＤＰ−０５０、ノズルタイプはサークルエッジノズル、乾燥塔寸法は２５００ｍｍφ×４８００ｍｍＨ）を用いて、噴霧乾燥を行った。
乾燥ガス導入量は２３ｍ^３／分、乾燥ガス入口温度は９０℃とした。また、噴霧ノズルとしては、直径３０ｍｍφで、３６０゜（環状）方向に水平噴霧可能な型式のものを使用し、ノズルのスラリー出口クリアランスは６００μｍ、スラリーを微細化する為の加圧気体流出口のクリアランスは３５０μｍとした。水性スラリー供給速度は、５６０ｇ／分、加圧気体流の供給速度は１２００Ｌ／分とした（気体流のガス線速は３３０ｍ／秒）。排気ガス温度は４５℃であった。
噴霧乾燥により得た粉体を９００℃で１０時間焼成し、リチウムマンガン複合酸化物を得た。この複合酸化物をボールミルで５分間解砕した。その結果、平均粒子径９μｍのほぼ球状の粒子が得られた。Ｘ線解折を測定したところ、立方晶のスピネル型リチウムマンガン複合化合物の構造を有していることが確認された。
【００６１】
【発明の効果】
本発明によれば、リチウム遷移金属複合酸化物への鉄粉などの混入を防止することができる。
【図面の簡単な説明】
【図１】実施例１３における磁力磁選機への水性スラリーの通過回数と水性スラリー中のＳＵＳ粉末の除去率との関係を示す図である。
【図２】噴霧乾燥に用いることができる噴霧乾燥機のノズル部分の断面を示す模式的側面図。
【符号の説明】
１　　ガス供給管
２　　水性スラリー供給管[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a lithium transition metal composite oxide containing at least lithium and a transition metal selected from manganese, cobalt and nickel. The lithium transition metal composite oxide obtained by the method of the present invention is useful as a positive electrode active material for a non-aqueous lithium secondary battery.
[0002]
[Prior art]
LiMnO₂, LiMn₂O₄, LiCoO₂, LiNiO₂Lithium transition metal composite oxide containing lithium and any one transition metal of manganese, cobalt and nickel; LiMn_xCo_yO₂, LiMn_xNi_yO₂, LiCo_xNi_yO₂(All of X + Y = 1) such as manganese, cobalt, and nickel; and lithium transition metal composite oxides containing at least two of them; It is known to use a lithium transition metal composite oxide substituted with another metal such as indium or the like as a positive electrode active material of a non-aqueous lithium secondary battery. In these lithium transition metal composite oxides, a lithium compound and manganese or other metal compounds are blended so as to have a metal composition equal to the composition of a desired lithium transition metal composite oxide, and the blend becomes a uniform composition. It is also known that they can be produced by sintering after sufficient mixing. One suitable method for making the composition a uniform composition is to wet-pulverize the composition as an aqueous slurry with a ball mill or tube mill.
[0003]
[Problems to be solved by the invention]
One of the problems when using a lithium transition metal composite oxide as a positive electrode active material of a lithium secondary battery is that the lithium transition metal composite oxide contains magnetic powder such as iron powder or stainless steel powder. There is something that can happen. It is thought that iron powder etc. is mainly derived from manganese, nickel, cobalt and other metal compounds used in the production of this composite oxide, but stainless steel powder and some iron powders etc. It is conceivable that these substances were mixed in from the apparatus. In any case, if a lithium transition metal composite oxide mixed with iron powder or the like is used as the positive electrode active material, the battery may not operate normally. This is presumably because the mixed iron powder or the like causes a micro short circuit. Accordingly, an object of the present invention is to provide a method for preventing mixing of magnetic powder such as iron powder into the obtained composite oxide when producing a lithium transition metal composite oxide.
[0004]
[Means for Solving the Problems]
According to the present invention, an aqueous slurry containing at least a transition metal compound and a lithium compound selected from the group consisting of a manganese compound, a nickel compound, and a cobalt compound is wet-pulverized and then fired to produce a lithium-transition metal composite oxide. In doing so, as the transition metal compound, use a magnetic powder such as iron powder that has been mixed and removed by magnetic force in advance or use an aqueous slurry by passing the aqueous slurry through a device that magnetically removes the magnetic powder. By removing the magnetic powder mixed therein, it is possible to prevent iron powder or the like from being mixed into the generated lithium transition metal composite oxide. The lithium compound may not be contained in the aqueous slurry to be subjected to wet pulverization, but may be mixed with the transition metal compound that has been subjected to wet pulverization and then subjected to firing.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, a transition metal compound selected from the group consisting of manganese, cobalt and nickel is mixed with water, if desired, together with other metal compounds, and pulverized as an aqueous slurry with a wet pulverizer. In one embodiment of the present invention, as the metal compound used for the preparation of the aqueous slurry, a magnetic compound such as iron powder that has been previously suctioned and removed by magnetic force is used. This makes it possible to remove, from the iron powder and the like mixed into the lithium transition metal compound, those derived from the raw material compound. In this case, it is most preferable to previously remove iron powder or the like by magnetic force from all of the raw material metal compounds in advance, but from a transition metal compound such as manganese which is a high risk of becoming a contamination source of iron powder or the like. Even if the magnetic powder is merely sucked and removed by the magnetic force, a considerable effect can be obtained. In addition, the suction removal of iron powder or the like by magnetic force from the raw material compound may be performed after the raw material compound is blended so as to have a target lithium transition metal composite oxide composition, or may be performed before blending. Is also good.
[0006]
In another embodiment of the present invention, iron powder and the like mixed in the aqueous slurry are suctioned and removed by passing the aqueous slurry through a device for sucking and removing magnetic powder by magnetic force. Of course, these two aspects can be used in combination. The suction removal of iron powder and the like mixed in from the aqueous slurry can be performed at any time from the preparation of the aqueous slurry to the end of wet grinding, but is preferably performed during or after grinding. . This makes it possible to remove iron powder contained in the particles of the metal compound as the raw material, iron powder and stainless steel powder mixed in from the pulverizer.
As the manganese compound, the cobalt compound, and the nickel compound used for preparing the aqueous slurry, those known to be usable as a raw material of the lithium transition metal composite oxide may be used. For example, as a manganese compound, Mn₂O₃, MnO₂, Mn₃O₄, MnCO₃, Mn (NO₃)₂, MnSO₄Manganese dicarboxylate, manganese citrate, manganese acetate and other fatty acid manganese, manganese oxyhydroxide, manganese halide and the like can be used. Among them, the valence of manganese is Mn close to the valence of manganese in the lithium transition metal composite oxide.₂O₃Or Mn₃O₄It is preferable to use Particularly preferred is Mn₂O₃It is.
[0007]
Nickel compounds include Ni (OH)₂, NiO, NiOOH, NiCO₃・ 2Ni (OH)₂・ 4H₂O, NiC₂O₄・ 2H₂O, Ni (NO₃)₂・ 6H₂O, NiSO₄, NiSO₄・ 6H₂O, fatty acid nickel, nickel halide and the like can be used. Among these, Ni (OH)₂, NiO, NiOOH, NiCO₃・ 2Ni (OH)₂・ 4H₂O, NiC₂O₄・ 2H₂It is preferable to use O or the like. Particularly preferred is Ni (OH)₂, NiO, NiOOH and the like.
[0008]
Co (OH) as the cobalt compound₂, CoO, Co₂O₃, Co₃O₄, Co (OAc)₂・ 4H₂O, CoCl₂, Co (NO₃)₂・ 6H₂O, Co (SO₄)₂・ 7H₂O or the like can be used. Preferably Co (OH)₂, CoO, Co₂O₃, Co₃O₄And so on. Particularly preferred is Co (OH)₂It is.
[0009]
The aqueous slurry contains other metal compounds in addition to the above-mentioned transition metal compound selected from the group consisting of manganese, cobalt and nickel, and the above-mentioned transition metal in the finally obtained lithium transition metal composite oxide is obtained. Can be partially substituted by this metal. Such metals (hereinafter sometimes referred to as substitution metals) include boron, aluminum, tin, copper, titanium, zinc, magnesium, gallium, calcium, silicon, vanadium, zirconium, antimony, ruthenium, lead, and hafnium. And tantalum. Among these, aluminum, magnesium, vanadium and the like are preferable, and aluminum is particularly preferable. These substituted metals may be contained in the aqueous slurry as oxides, hydroxides, nitrates, carbonates, dicarboxylates, fatty acid salts and the like. Lithium transition metal composite oxides in which some of the transition metals have been substituted with these substituted metals, when used as the positive electrode active material of non-aqueous lithium secondary batteries, can exhibit superior properties to those of the unsubstituted lithium secondary batteries. is there. The ratio between the transition metals in the aqueous slurry and the ratio between the transition metal and the substitution metal are made to match the composition of the finally obtained lithium transition metal composite oxide. The specific composition ratio is selected according to the desired properties of the finally obtained lithium transition metal composite oxide. For example, when manganese is used as the transition metal, the substitution metal is preferably present in at least 2.5 atomic%, usually 5 atomic% or more based on the total of manganese and the substitution metal. However, if the ratio of the substitution metal is too high, the capacity of the battery using the same as the positive electrode active material decreases. Therefore, the ratio of the substitution metal is generally preferably 30 atomic% or less, particularly preferably 20 atomic% or less. . When the transition metal is cobalt, the content of the substitution metal is preferably set to 25 atomic% or less based on the total of the cobalt and the substitution metal.
[0010]
Lithium constituting the finally obtained lithium transition metal composite oxide may be contained in the aqueous slurry. As the lithium compound, Li₂CO₃, LiNO₃, LiOH, LiOH.H₂O, LiCl, LiI, Li₂O, lithium fatty acids such as lithium dicarboxylate, lithium citrate and lithium acetate, and alkyl lithium may be used. Among these, Li₂CO₃, LiNO₃, LiOH ・ H₂It is preferable to use a water-soluble lithium compound such as O and lithium acetate. Particularly preferred is LiOH.H₂O. The preferred ratio of lithium to transition metal (the sum of the transition metal and the substitution metal, if any) is different for each transition metal. For example, when the transition metal is manganese, the atomic ratio of lithium to manganese is usually 40 to 60 atomic%. It is preferably 45 to 55 atomic%, particularly preferably 50 to 55 atomic%. When the transition metal is nickel or cobalt, the atomic ratio of lithium to these is preferably 100 to 110 atomic%. When the ratio of lithium is small, the rock salt domain of the layered rock salt structure of the lithium transition metal composite oxide becomes large. Conversely, when the ratio of lithium is large, lithium replaces nickel and cobalt sites of the lithium transition metal composite oxide. When two or three transition metals are used in combination, the ratio of lithium may be determined according to the atomic ratio of lithium to the main transition metal. For example, when a small amount of manganese is used in combination with nickel, it is preferable to use 100 to 110 atomic% of lithium with respect to (nickel + manganese + substituted metal).
[0011]
The ratio of the above metal compound in the aqueous slurry is usually 10% by weight or more, preferably 12.5% by weight or more. When the ratio of the metal compound is small, the production efficiency decreases, and the spherical particles generated when the aqueous slurry is spray-dried in a later step are easily damaged. If the ratio of the metal compound is too high, handling becomes difficult and it is difficult to maintain the uniformity of the aqueous slurry. Therefore, the upper limit is preferably 50% by weight or less, particularly preferably 35% by weight or less.
[0012]
As a wet pulverizer for pulverizing the aqueous slurry, a medium stirring type pulverizer such as a ball mill or a tube mill may be used. The pulverization is performed so that the average particle diameter of the solid matter of the slurry is 2 μm or less. It is preferable to carry out the treatment so that the average particle diameter is 1 μm or less, particularly 0.5 μm or less. If the average particle diameter of the solid matter in the slurry is large, the sphericity of the particles obtained in the subsequent spraying step tends to decrease, and the powder packing density tends to decrease. As a further big problem, the reactivity in the firing step is reduced. The average particle diameter of the solid matter in the slurry is preferably as small as possible, but it is not necessary to make the average particle diameter smaller than 0.01 μm in consideration of pulverization cost. From the viewpoint of cost and effect, it is preferable that the pulverization is performed so that the average particle diameter is 0.05 μm or more, particularly 0.1 μm or more.
[0013]
Suction removal of the magnetic powder from the aqueous slurry by magnetic force can be performed at any stage before, during, or after wet pulverization. Usually, during or after wet grinding. As a result, iron powder and the like contained in the particles of the raw material compound, iron powder and stainless steel powder mixed from the wet pulverizer can be removed by suction.
[0014]
In order to sufficiently remove the magnetic powder in the aqueous slurry, the aqueous slurry is preferably passed through a device for removing the magnetic powder two or more times, more preferably three or more times. Although the upper limit of the number of passes is arbitrary, it is usually 20 times or less, and 10 times or less is often sufficient. A commercially available magnetic separator equipped with a magnetic matrix can be used as an apparatus for removing the magnetic powder, and the inside of the magnetic matrix is controlled at 0.01 m / sec to 2 m / sec, particularly 0.05 m / sec to 0.5 m / sec. Preferably, the aqueous slurry is passed.
[0015]
The magnetic flux density of the magnetic matrix must be strong enough to adsorb iron powder and the like but not to adsorb compounds such as transition metals, substituted metals and lithium in the aqueous slurry. Table 1 shows magnetic flux densities at which metal compounds usually contained in iron powder and aqueous slurry are adsorbed. 6000 gauss or more indicates that 6000 gauss was not adsorbed. SUS powder (fired) is obtained by firing stainless steel powder at 900 ° C. for 10 hours. For the measurement, the powder of the sample was placed on a horizontally laid paper, and a neodymium magnet (surface magnetic flux density: 6000 gauss) was gradually lowered from a position of 10 cm above to approach the sample, and the sample was attracted to the magnet. The measurement was performed by measuring the magnetic flux density on the surface of the paper when the measurement was performed using a magnetometer (TM501) manufactured by Kanetec Corporation.
[0016]
[Table 1]

[0017]
The magnetic flux density of the magnetic matrix of the magnetic force separator is preferably 100 gauss or more, particularly 200 gauss or more in order to remove iron powder. In order to remove the stainless steel powder, the thickness is preferably 400 gauss or more, particularly 700 gauss or more. In order to sufficiently remove iron powder and the like and not to adsorb other metal compounds, the magnetic matrix has a magnetic flux density of 1000 gauss or more, and the upper limit is the magnetic flux density at which the metal compounds contained in the aqueous slurry are adsorbed. It is preferable to set the magnetic flux density to be less than 100 gauss lower than the magnetic flux density at which the metal compound is adsorbed.
[0018]
In a preferred embodiment of the present invention, a part of the aqueous slurry is withdrawn from the wet mill during the milling step, and the magnetic slurry is removed by passing the aqueous slurry through a magnetic powder removing device by a magnetic force and returning to the wet mill. Do. Generally, an aqueous slurry becomes hot due to frictional heat during wet pulverization, and the viscosity increases accordingly. Therefore, at the time of wet pulverization, a part of the aqueous slurry is extracted from the wet pulverizer and returned to the wet pulverizer through a storage tank equipped with a cooling coil, a cooling jacket, and the like. It is preferable to control the temperature of the aqueous slurry to 20 to 50C, particularly to 25 to 40C. The temperature of the aqueous slurry can be easily adjusted by controlling the temperature and amount of cooling water supplied to the cooling coil and cooling jacket of the storage tank. If the ambient temperature is low during each period or the like, the temperature may be maintained in the above temperature range without cooling with cooling water due to natural heat radiation from the circulation path depending on the circulation speed. When a magnetic powder removing device is installed in the circulation path for cooling the aqueous slurry, the cooling of the aqueous slurry and the removal of iron powder and the like from the aqueous slurry can be performed simultaneously. That is, according to this method, the stainless steel powder generated from the wet mill, the iron powder released from the particles of the metal compound of the raw material accompanying the pulverization, and the like are sequentially removed by the magnetic powder removing device with the circulation of the aqueous slurry. Since it is gradually removed, there is no need to pass the aqueous slurry through the magnetic powder removing device again after the completion of pulverization to remove iron powder and the like. In the case where a part of the aqueous slurry is extracted from the wet-type pulverizer during the pulverization and passed through the magnetic powder removing device, the number of passes is calculated by the following equation.
[0019]
(Equation 1)
Number of passages = amount of aqueous slurry that has passed through the removal device / aqueous slurry in the wet grinding system
amount
[0020]
The aqueous slurry pulverized to a desired average particle size by a wet pulverizer is preferably spray-dried to obtain a powder. The spray drying is preferably performed at a viscosity of the aqueous slurry of 50 mPa · S or more and 3000 mPa · S or less. If the viscosity is smaller than this, the particle size of the powder to be produced becomes too small, or the powder is easily broken. On the other hand, if the viscosity is higher than this, handling of the aqueous slurry becomes difficult. The lower limit of the viscosity of the aqueous slurry is preferably 100 mPa · S or more, more preferably 200 mPa · S or more, and the upper limit is preferably 2000 mPa · S or less, particularly 1600 mPa · S or less. The viscosity of the aqueous slurry is measured using a BM type viscometer. That is, the rotor of the viscometer is rotated in the aqueous slurry at room temperature, and the viscosity is calculated from the resistance (twisting force) applied to the rotation axis.
[0021]
The spray drying of the aqueous slurry may be performed according to a conventional method. For example, a method in which an aqueous slurry is supplied into an airflow spouted from a nozzle at a high speed and scattered and dried as droplets can be adopted. Usually, an air flow is used as the air flow, and the air is jetted at a speed of 100 m / sec or more. If the ejection speed is low, it is difficult to form an appropriate droplet. The jet velocity of the air current is preferably 200 m / sec or more, particularly preferably 300 m / sec or more. The upper limit is usually 1000 m / sec or less. As the nozzle, for example, the nozzle described in Japanese Patent No. 2797080 may be used. Preferably, a four-fluid nozzle as shown in FIG. 2 is used. The spray drying is preferably performed so that the average particle diameter of the resulting powder is 50 μm or less, particularly 30 μm or less. However, it is preferable to perform spray drying so that the average particle diameter is 4 μm or more, particularly 5 μm or more, since the production of a substance having an average particle diameter that is too small is difficult and there is no advantage associated with the small particle diameter. The lower limit of the temperature of the drying gas introduced into the spray dryer is usually 50 ° C. or higher, preferably 70 ° C. or higher, and the upper limit is 120 ° C. or lower, preferably 100 ° C. or lower. If the temperature of the drying gas is too low, dew condensation occurs inside the spray dryer, and the powder sticks or clogs. On the other hand, if the temperature is too high, the resulting powder will have many hollow particles, and the packing density of the powder will decrease.
[0022]
The powder obtained by spray drying is then calcined to convert to a lithium transition metal composite oxide. When the lithium compound is not contained in the aqueous slurry or only a small amount is contained, the lithium compound powder is blended with the powder obtained by spray drying, mixed well, and fired to obtain a uniform composition. As the lithium compound, those described above may be used. The lithium compound is used after being pulverized to an average particle diameter of 500 μm or less, preferably 100 μm or less. The smaller the average particle diameter is, the easier the uniform mixing with the transition metal compound is, and the better the reaction at the time of firing proceeds. Therefore, the lithium compound is preferably pulverized to the smallest possible particle size, more preferably 50 μm or less, and further preferably 20 μm or less. Most preferably, it is pulverized to 5 μm or less. However, as the particle size becomes smaller, the effect associated with pulverization gradually decreases and the cost of pulverization also increases, so that it is not advantageous to make the particle size smaller than 0.01 μm. Usually, pulverization is performed so as to be 0.1 μm or more, particularly 0.2 μm or more. It is most preferable to pulverize it to 0.5 μm or more from the viewpoint of cost and effect. Sintering may be performed according to a conventional method. As the firing device, a conventional firing device such as a box furnace, a tubular furnace, a tunnel furnace, and a rotary kiln can be used. The firing temperature and the like may be appropriately selected depending on the intended lithium transition metal composite oxide. For example, when the transition metal is manganese, it is calcined at 600 to 900 ° C. in an oxygen atmosphere and then gradually cooled to 500 ° C. or less at a rate of 10 ° C./min or less, or at 600 to 900 ° C. in an air or oxygen atmosphere. And then annealing at a temperature of about 400 ° C. in an oxygen atmosphere. The firing method is described in detail in JP-A-9-259880, 306490, and 306493. The produced lithium manganese composite oxide is LiMn.₂O₄Lithium manganate or LiMnO having a spinel structure having a basic composition of₂Is a layered lithium manganate having a basic composition of, but a spinel-type lithium manganate is preferred because it is easier to produce and has excellent cycle characteristics when used as a positive electrode active material.
One of the preferable compositions of the lithium manganese composite oxide having a spinel structure produced by firing is represented by the following formula.
[0023]
(Equation 2)
Li_bMn_2-aMaO₄
[0024]
(M is at least one selected from the group consisting of B, Al, Sn, Cu, Ti, Zn, Co and Ni, 0 <b ≦ 1.5, 0 <a ≦ 1)
Among them, those represented by the following formula are preferred.
[0025]
(Equation 3)
Li_YMn_2-xAl_xO₄
[0026]
(0 <X ≦ 1.0, 0.9 ≦ Y ≦ 1.1)
In any of the above equations, the amount of oxygen may vary.
When the transition metal is nickel or cobalt, firing may be performed at 700 ° C. to 1050 ° C. in an air or oxygen atmosphere. The lower limit of the firing temperature is preferably 725 ° C, particularly preferably 750 ° C, and the upper limit is preferably 1000 ° C or lower, particularly 950 ° C or lower. The most preferred firing temperature is 800-900C. Further, in order to obtain a lithium transition metal composite oxide having few crystal defects, it is preferable to gradually cool after firing, for example, slowly cool at a rate of 5 ° C./min or less. The sintering time is usually 30 minutes or more at the above temperature, and at most 50 hours or less is sufficient. If the calcination time is too long, crushing may be difficult in a subsequent step, so it is preferably 25 hours or less, particularly preferably 20 hours or less. Generally, the most preferred firing time is 7 to 15 hours. One of the preferable compositions of the lithium-nickel composite oxide formed by firing is represented by the following formula.
[0027]
(Equation 4)
Li_XNi_YQ_(1-Y)O₂
[0028]
(Q is at least one selected from the group consisting of Co, Al, Mg, Ga, Ti and Ca, and 0 <X ≦ 1.2, 0.5 ≦ Y <1.0)
Among them, those represented by the following formula are preferred.
[0029]
(Equation 5)
Li_XNi_YCo_ZQ '_(1-YZ)O₂
[0030]
(Q ′ is at least one selected from the group consisting of Co, Al, Mg, Ga, Ti and Ca, and 0 <X ≦ 1.2, 0.5 ≦ Y <1.0, 0 <Z ≦ 0 .5)
When nickel and manganese are used in combination as the transition metal, the transition metal is preferably represented by the following formula.
[0031]
(Equation 6)
Li_XNi_YMn_ZQ_(1-YZ)O₂
[0032]
(Q is at least one selected from the group consisting of Co, Al, Mg, Ga, Ti and Ca, and 0 <X ≦ 1.2, 1 ≦ Y / Z ≦ 9, 0 <(1-Y− Z) ≦ 0.5)
One preferred composition of the lithium-cobalt transition metal composite oxide produced by firing is represented by the following formula.
[0033]
(Equation 7)
Li_XCo_1-YA_YO₂
[0034]
(A represents at least one selected from the group consisting of B, Mg, Si, Cu, Ti, V, Mn, Ni, Sn, Zr, Sb, Nb, Ru, Pb, Hf and Ta, and 0 <X ≦ 1.2, 0 ≦ Y ≦ 0.25)
The lithium transition metal composite oxide obtained by firing is crushed to form a positive electrode active material. Crushing is performed using a ball mill, jet mill, pin mill, or the like so that the average particle size is 100 μm or less, preferably 50 μm or less. Although the crushed lithium transition metal composite oxide can be used as it is as the positive electrode active material, it is preferable to classify and remove the large particle size one. Usually, it is preferable to obtain particles having a particle size of 100 μm or less, particularly 50 μm or less, by an airflow classifier using gravity, inertia force, centrifugal force or the like. In addition, iron powder and the like may be mixed from the apparatus in these crushing and classifying steps, so it is preferable to remove iron powder and the like by magnetic force again after these steps. As the removing device, the same device as used for removing iron powder and the like in the aqueous slurry may be used.
[0035]
In this specification, the average particle diameter of the solid content in the slurry, the average particle diameter of the powder after spray drying, and the average particle diameter of the lithium transition metal composite oxide are known laser diffraction / scattering particle size distributions. Measure with a measuring device. In this method, a slurry or powder is dispersed in a dispersion medium, a laser beam is applied to the sample solution, and scattered light that is incident on particles and scattered (diffracted) is detected by a detector. The scattering angle θ (the angle between the incident direction and the scattering direction) of the detected scattered light is forward scattering (0 <θ <90 °) for a large particle, and side scattering or back scattering (90 for a small particle).゜ <θ <180 °). From the measured angle distribution value, the particle size distribution is calculated using information such as the wavelength of the incident light and the refractive index of the particles. Further, the average particle size is calculated from the obtained particle size distribution. As a dispersion medium used in the measurement, for example, a 0.1% by weight aqueous solution of sodium hexametaphosphate can be mentioned.
[0036]
The lithium transition metal composite oxide obtained in the present invention is suitable for use as an active material of a positive electrode of a lithium secondary battery.
The positive electrode can be usually formed by applying and drying a slurry containing the above-described positive electrode active material, binder and conductive agent on a current collector. The proportion of the positive electrode active material in the active material layer formed by coating and drying is usually 10% by weight or more, preferably 30% by weight or more, more preferably 50% by weight or more, and usually 99.9% by weight or less. It is preferably at most 99% by weight. If the amount of the positive electrode active material is too large, the strength of the positive electrode tends to be insufficient. If the amount is too small, the capacity becomes insufficient.
[0037]
As the conductive agent, carbon black such as natural graphite, artificial graphite, and acetylene black, and amorphous carbon such as needle coke can be used. The proportion of the conductive agent in the active material layer is usually at least 0.01% by weight, preferably at least 0.1% by weight, more preferably at least 1% by weight, and usually at most 50% by weight, preferably at most 20% by weight. , More preferably 10% by weight or less. If the amount of the conductive agent is too large, the capacity becomes insufficient, and if the amount is too small, the electric conductivity becomes insufficient.
[0038]
Examples of the binder include fluorine polymers such as polyvinylidene fluoride, polytetrafluoroethylene, fluorinated polyvinylidene fluoride, and fluoro rubber, EPDM (ethylene-propylene-diene terpolymer), SBR ( Styrene-butadiene rubber), NBR (acrylonitrile-butadiene rubber), polyvinyl acetate, polymethyl methacrylate, polyethylene, nitrocellulose and the like can be used. The proportion of the binder in the active material layer is usually 0.1% by weight or more, preferably 1% by weight or more, more preferably 5% by weight or more, and usually 80% by weight or less, preferably 60% by weight or less, More preferably, it is at most 40% by weight. When the amount is too large, the capacity becomes insufficient, and when the amount is too small, the strength becomes insufficient.
[0039]
In addition, as a solvent used when preparing a slurry, an organic solvent that dissolves or disperses a binder is usually used. For example, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N, N-dimethylaminopropylamine, ethylene oxide, tetrahydrofuran and the like can be used. In some cases, a dispersant, a thickener, and the like are added to water to form a slurry with a latex such as SBR.
[0040]
The thickness of the active material layer is usually about 10 to 200 μm.
As the current collector, a metal such as aluminum, stainless steel, and nickel-plated steel is used, and aluminum is preferable.
The active material layer obtained by coating and drying is preferably compacted by a roller press or the like in order to increase the packing density of the electrode material.
[0041]
As the negative electrode active material used in the nonaqueous lithium secondary battery of the present invention, a carbon material is preferable. Examples of such carbon materials include natural or artificial graphite, petroleum-based coke, coal-based coke, carbide of petroleum pitch, carbide of coal-based pitch, carboxy of resin such as phenolic resin and crystalline cellulose, and partially carbonized these. Examples include carbon materials, furnace black, acetylene black, pitch-based carbon fibers, PAN-based carbon fibers, and mixtures of two or more of these. The negative electrode active material is usually formed into a slurry together with a binder and, if necessary, a conductive agent, and then applied and dried on a current collector to form a negative electrode. A lithium metal itself or a lithium alloy such as a lithium aluminum alloy can be used as the negative electrode. As the binder and the conductive agent used for the negative electrode, those similar to those used for the positive electrode may be used.
[0042]
The thickness of the negative electrode active material is usually about 10 to 200 μm.
As the current collector of the negative electrode, a metal such as copper, nickel, stainless steel, and nickel-plated steel is usually used, and copper is preferable.
As the non-aqueous electrolyte, a solution in which various electrolytic salts are dissolved in a non-aqueous solvent can be used.
As the non-aqueous solvent, for example, carbonates, ethers, ketones, sulfolane compounds, lactones, nitriles, halogenated hydrocarbons, amines, esters, amides, phosphate ester compounds and the like can be used. it can. Typical of these are propylene carbonate, ethylene carbonate, chloroethylene carbonate, trifluoropropylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, vinylene carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4 -Dioxane, 4-methyl-2-pentanone, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, 1,3-dioxolan, 4-methyl-1,3-dioxolan, diethyl ether, sulfolane , Methylsulfolane, acetonitrile, propionitrile, benzonitrile, butyronitrile, valeronitrile, 1,2-dichloroethane, dimethylformamide, dimethyls Sulfoxide, trimethyl phosphate, can be mentioned triethyl phosphate, etc., may be used such as a single or two or more kinds of mixed solvents.
[0043]
Among the above non-aqueous solvents, it is preferable to use a high dielectric constant solvent for dissociating the electrolyte. The high dielectric constant solvent means a compound having a relative dielectric constant at 25 ° C. of about 20 or more. Among the high dielectric constant solvents, it is preferable that ethylene carbonate, propylene carbonate, and a compound in which hydrogen atoms thereof are replaced with another element such as halogen or an alkyl group are contained in the electrolytic solution. The proportion of the high dielectric constant solvent in the electrolyte is usually at least 20% by weight, preferably at least 30% by weight, more preferably at least 40% by weight. If the content of the high dielectric constant solvent is small, desired battery characteristics may not be obtained.
[0044]
As the electrolytic salt, any of conventionally known electrolytic salts can be used.₄, LiAsF₆, LiPF₆, LiBF₄, LiB (C₆H₅)₄, LiCl, LiBr, LiCH₃SO₃, LiCF₃SO₃, LiN (SO₂CF₃)₂, LiN (SO₂C₂F₅)₂, LiC (SO₂CF₃)₃, LiN (SO₃CF₃)₂And the like.
[0045]
Also, CO₂, N₂O, CO, SO₂Such as gas and polysulfide Sx^2-An additive such as vinylene carbonate, catechol carbonate, or the like, which forms a good film that enables efficient charge and discharge of lithium ions on the surface of the negative electrode, may be present in the electrolyte at an arbitrary ratio.
Instead of the electrolytic solution, a solid polymer electrolyte which is a conductor of an alkali metal cation such as lithium ion can be used. In addition, a semi-solid electrolyte in which the electrolyte is made non-fluidized by a polymer can be used. In a lithium secondary battery, an electrolyte layer can be provided between the positive electrode and the negative electrode by using various materials as described above.
[0046]
Usually, a separator is provided between the positive electrode and the negative electrode. As the separator, a microporous polymer film is used, and as its material, nylon, polyester, cellulose acetate, nitrocellulose, polysulfone, polyacrylonitrile, polyvinylidene fluoride, tetrafluoroethylene, polypropylene, polyethylene, polybutene, etc. Of polyolefin-based polymers. In addition, a nonwoven fabric filter of glass fiber or the like, or a composite nonwoven fabric filter of glass fiber and polymer fiber can be used. The chemical and electrochemical safety of the separator is an important factor, and in this regard, the material is preferably a polyolefin-based polymer. Preferably, there is.
[0047]
In the case of a polyethylene separator, it is preferably ultrahigh molecular weight polyethylene from the viewpoint of high-temperature shape retention, and the lower limit of the molecular weight is preferably 500,000, more preferably 1,000,000, and most preferably 1.5 million. On the other hand, the upper limit of the molecular weight is preferably 5,000,000, more preferably 4,000,000, and most preferably 3,000,000. If the molecular weight is too large, the fluidity is so low that the pores of the separator may not be closed when heated.
[0048]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples. SUS indicates stainless steel.
Example 1
Mn₂O₃A sample was prepared by mixing 1 g of iron powder having a particle size of about 100 μm with # 10 g. The sample was spread on paper, and a magnet having a magnetic flux density of 6000 Gauss was approached from above until the magnetic force applied to the sample became 2000 Gauss. In this state, the paper was swung right and left for 5 minutes. As a result, 1 g of iron powder was recovered by the magnet.
[0049]
Example 2
A magnetic powder was collected by a magnet in the same manner as in Example 1 except that a sample in which 1 g of SUS powder (unfired) having a particle size of about 100 μm was mixed instead of the iron powder was used. As a result, 1 g of SUS powder (unfired) was recovered.
Example 3
A magnetic powder was recovered by a magnet in the same manner as in Example 1 except that a sample in which 1 g of SUS powder (fired) having a particle size of about 100 μm was mixed instead of the iron powder was used. As a result, 1 g of SUS powder (baked) was recovered.
[0050]
Example 4
The magnetic powder was collected by the magnet in the same manner as in Example 1 except that the magnet was brought close to the magnetic force applied to the sample to 500 gauss. 1 g of iron powder was recovered.
Example 5
Mn₂O₃Instead of 10g, Ni (OH)₂A magnetic powder was collected using a magnet in the same manner as in Example 2 except that the sample using # 10 g was used as a sample, and the magnet was brought close to the magnetic force received by the sample until it reached 2500 Gauss. As a result, 1 g of SUS powder (unfired) was recovered.
[0051]
Example 6
Mn₂O₃Co (OH) instead of 10g₂A magnetic powder was collected using a magnet in the same manner as in Example 2 except that a sample using # 10 g was used as a sample, and the magnet was approached until the magnetic force received by the sample became 2000 gauss. As a result, 1 g of SUS powder (unfired) was recovered.
Example 7
Mn₂O₃, AlOOH, LiOH.H₂O was mixed in a final composition of the spinel-type lithium manganese composite oxide in a ratio of Li: Mn: Al = 1.04: 1.84: 0.12 (atomic ratio) to obtain 10 g of particles. A sample was prepared by mixing 1 g of iron powder having a diameter of about 100 μm. The sample was spread on paper, and a magnet having a magnetic flux density of 6000 Gauss was approached from above until the magnetic force applied to the sample became 2000 Gauss. In this state, the paper was shaken from side to side for 5 minutes. As a result, 1 g of iron powder was recovered by the magnet.
[0052]
Example 8
Mn₂O₃, AlOOH, LiOH.H₂Pure water was added to a mixture of O and Li: Mn: Al = 1.04: 1.84: 0.12 (atomic ratio) in the final composition of the spinel-type lithium manganese composite oxide. In addition, a slurry having a solid concentration of 30% by weight was prepared. The obtained slurry was crushed by a circulating medium agitation type wet crusher and crushed until the average particle diameter of the solid content in the slurry became 0.3 μm. 40 ml of the pulverized slurry and 1 g of iron powder having a particle size of about 100 μm were placed in a 50 ml beaker and stirred, and then stirred with an alnico magnet of 50 mm × 10 mm × 10 mm and a magnetic flux density of 2200 gauss for 5 minutes. As a result, 1 g of iron powder was recovered by the magnet. This operation was repeated to prepare one liter of the slurry after the iron powder was recovered. The slurry is sprayed using a spray dryer (Fujisaki Electric Co., Ltd., Micro Mist Dryer MDP-050, nozzle type: circle edge nozzle, drying tower dimensions: 2500 mmφ × 4800 mmH) provided with a nozzle having a droplet refining mechanism. Drying was performed.
[0053]
The amount of dry gas introduced into the drying tower is 23m³/ Min, and the drying gas inlet temperature was 90 ° C. As the spray nozzle, a nozzle having a diameter of 30 mmφ and a type capable of horizontal spraying in a 360 ° (annular) direction is used, a slurry outlet clearance of the nozzle is 600 μm, and a pressurized gas outlet for atomizing the slurry is used. The clearance was set at 350 μm. The slurry supply speed was 560 g / min, and the supply speed of the pressurized gas flow was 1200 L / min (the gas linear velocity of the gas flow was 330 m / sec). The exhaust gas temperature was 45 ° C.
The particles obtained by spray drying were fired at 900 ° C. for 10 hours to obtain a lithium manganese composite oxide. This composite oxide was crushed with a ball mill for 5 minutes. As a result, substantially spherical particles having an average particle diameter of 9 μm were obtained. X-ray diffraction confirmed that it had the structure of a cubic spinel-type lithium manganese composite compound.
[0054]
Example 9
Mn₂O₃Instead of 10g, Li_1.04Mn_1.84Al_0.12O₄Magnetic powder was collected in the same manner as in Example 2 except that a sample using # 10 g was used as a sample, and the magnet was brought close to the magnetic force received by the sample until it reached 2500 Gauss. As a result, 1 g of SUS powder (unfired) was recovered.
[0055]
Example 10
Mn₂O₃Instead of 10g, Li_1.04Ni_0.8Co_0.15Al_0.05O₂A magnetic powder was collected in the same manner as in Example 2 except that a sample using # 10 g was used as a sample, and the magnet was brought close to the magnetic force applied to the sample until it reached 4000 Gauss. As a result, 1 g of SUS powder (unfired) was recovered.
[0056]
Example 12
Mn₂O₃Instead of 10g, LiCoO₂Magnetic powder was collected in the same manner as in Example 2 except that a sample using 10 g was used as a sample, and the magnet was brought closer to the sample until the magnetic force received by the sample became 5000 Gauss. As a result, 1 g of SUS powder (unfired) was recovered.
[0057]
Example 13
Mn₂O₃, AlOOH, LiOH.H₂792 g of a mixture of O and Li: Mn: Al = 1.04: 1.84: 0.12 (atomic ratio) in the final composition of the spinel-type lithium manganese composite oxide, and particles 8 g of SUS powder (unfired) having a diameter of 2 to 10 μm was mixed with 3200 g of demineralized water to prepare an aqueous slurry having a solid concentration of 20% by weight. This aqueous slurry was applied three times at a speed of 0.3 m / sec to an L-4 wet high magnetic force magnetic separator manufactured by Nihon Elise Magnetics Co., Ltd. having a matrix having a length of 0.5 m and a magnetic flux density of 2000 Gauss. Let it pass. The result is shown in FIG.
[0058]
The SUS powder removal rate on the vertical axis is a percentage of the weight of the SUS powder recovered by passing the aqueous slurry through a high magnetic force magnetic separator, based on the weight of 8 g of the SUS powder contained in the aqueous slurry.
The measuring method was as follows. First, the adhered substance of the matrix was recovered by washing with water, and the recovered substance was dried with a dryer to obtain a powder. After dissolving this powder with hydrochloric acid, the weight of the iron element in the powder was measured by ICP spectroscopy. The weight of the SUS powder attached to the matrix was calculated in advance from the value of the content of the iron element in the SUS powder used for preparing the aqueous slurry measured by ICP spectroscopy and the weight of the iron element measured above.
[0059]
Example 14
Mn₂O₃, AlOOH, LiOH.H₂792 g of a mixture of O and Li: Mn: Al = 1.04: 1.84: 0.12 (atomic ratio) in the final composition of the spinel-type lithium manganese composite oxide, and particles 8 g of SUS powder (unfired) having a diameter of 2 to 10 μm and 3200 g of demineralized water were supplied to a mixing tank and mixed to obtain an aqueous slurry. This aqueous slurry was supplied from a mixing tank to a wet pulverizer and pulverized until the average particle diameter became 0.3 μm. A part of the aqueous slurry was extracted during the pulverization, passed through a L-4 wet high magnetic force magnetic separator manufactured by Nippon Ellies Magnetics Co., Ltd. having a magnetic flux density of 2000 Gauss at 0.3 m / sec, and then mixed. And returned to the wet mill. The temperature of the aqueous slurry in the pulverizer was maintained at 29-34 ° C. When the aqueous slurry was passed through the magnetic separator 10 times, 8 g of SUS powder was recovered by the matrix of the wet magnetic separator.
[0060]
The pulverized aqueous slurry was then sprayed with a spray dryer (Microsaki MDP-050, manufactured by Fujisaki Electric Co., Ltd., nozzle type: circle edge nozzle, drying tower dimensions: 2500 mmφ × 4800 mmH) provided with a nozzle having a droplet atomizing mechanism. Spray drying was performed.
Dry gas introduction amount is 23m³/ Min, and the drying gas inlet temperature was 90 ° C. As the spray nozzle, a nozzle having a diameter of 30 mmφ and capable of horizontal spraying in a 360 ° (annular) direction is used, and a slurry outlet clearance of the nozzle is 600 μm, and a pressurized gas outlet for atomizing the slurry is used. The clearance was 350 μm. The feed rate of the aqueous slurry was 560 g / min, and the feed rate of the pressurized gas stream was 1200 L / min (the gas linear velocity of the gas stream was 330 m / sec). The exhaust gas temperature was 45 ° C.
The powder obtained by spray drying was fired at 900 ° C. for 10 hours to obtain a lithium manganese composite oxide. This composite oxide was crushed with a ball mill for 5 minutes. As a result, substantially spherical particles having an average particle diameter of 9 μm were obtained. When the X-ray diffraction was measured, it was confirmed to have the structure of a cubic spinel-type lithium manganese composite compound.
[0061]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, mixing of iron powder etc. into a lithium transition metal composite oxide can be prevented.
[Brief description of the drawings]
FIG. 1 is a diagram showing the relationship between the number of times an aqueous slurry has passed through a magnetic force magnetic separator and the removal rate of SUS powder in the aqueous slurry in Example 13.
FIG. 2 is a schematic side view showing a cross section of a nozzle portion of a spray dryer that can be used for spray drying.
[Explanation of symbols]
1 Gas supply pipe
2) Aqueous slurry supply pipe

Claims (15)

An aqueous slurry containing a transition metal compound and a lithium compound selected from the group consisting of at least a manganese compound, a nickel compound, and a cobalt compound is wet-ground and then calcined, or at least a manganese compound, a nickel compound, and a cobalt compound. In a method for producing a lithium transition metal composite oxide in which an aqueous slurry containing a selected transition metal compound is wet-pulverized and then mixed with a lithium compound and fired, magnetic powder mixed as a transition metal compound is previously magnetized. A method characterized by using a substance removed by suction. An aqueous slurry containing a transition metal compound and a lithium compound selected from the group consisting of at least a manganese compound, a nickel compound, and a cobalt compound is wet-ground and then calcined, or at least a manganese compound, a nickel compound, and a cobalt compound. In a method for producing a lithium transition metal composite oxide, in which an aqueous slurry containing a selected transition metal compound is wet-pulverized and then mixed with a lithium compound and fired, magnetic powder mixed in the aqueous slurry is attracted by magnetic force. A method characterized by firing after removal. A step of wet-grinding an aqueous slurry containing a lithium compound and a transition metal compound selected from the group consisting of at least a manganese compound, a nickel compound and a cobalt compound; a step of spray-drying the wet-milled aqueous slurry to obtain a powder; The method for producing a lithium transition metal composite oxide, which sequentially passes through the steps of firing the obtained powder to form a lithium transition metal composite oxide and crushing the obtained lithium transition metal composite oxide, The magnetic powder mixed as a transition metal compound is subjected to a process of sucking and removing by magnetic force, or the aqueous slurry is mixed into the aqueous slurry by passing through a device for sucking and removing the magnetic powder by magnetic force. A method comprising removing magnetic powder or performing at least one magnetic powder removal treatment. A step of wet-pulverizing an aqueous slurry containing at least a transition metal compound selected from the group consisting of a manganese compound, a nickel compound and a cobalt compound; a step of spray-drying the wet-pulverized aqueous slurry to obtain a powder; Production of lithium transition metal composite oxide through successive steps of mixing lithium compound into sintering and firing to obtain lithium transition metal composite oxide, and sequentially crushing the obtained lithium transition metal composite oxide In the method, a magnetic powder mixed as a transition metal compound is subjected to a process of sucking and removing by magnetic force, or an aqueous slurry is passed through a device for sucking and removing magnetic powder by magnetic force and mixed into the aqueous slurry. Or removing at least one of the magnetic powders. A step of wet-grinding an aqueous slurry containing a lithium compound and a transition metal compound selected from the group consisting of at least a manganese compound, a nickel compound and a cobalt compound; a step of spray-drying the wet-milled aqueous slurry to obtain a powder; Baking the obtained powder to form a lithium transition metal composite oxide, and a method for producing a lithium transition metal composite oxide, which sequentially passes through the steps of crushing the obtained lithium transition metal composite oxide. And removing the mixed magnetic powder by passing the wet-pulverized aqueous slurry through a device for sucking and removing magnetic powder by magnetic force. A step of wet-pulverizing an aqueous slurry containing at least a transition metal compound selected from the group consisting of a manganese compound, a nickel compound and a cobalt compound; a step of spray-drying the wet-pulverized aqueous slurry to obtain a powder; Production of lithium transition metal composite oxide through successive steps of mixing lithium compound into sintering and firing to obtain lithium transition metal composite oxide, and sequentially crushing the obtained lithium transition metal composite oxide A method wherein the wet-milled aqueous slurry is passed through a device for sucking and removing magnetic powder by magnetic force to remove mixed magnetic powder. A step of wet-grinding an aqueous slurry containing a lithium compound and a transition metal compound selected from the group consisting of at least a manganese compound, a nickel compound and a cobalt compound; a step of spray-drying the wet-milled aqueous slurry to obtain a powder; Baking the obtained powder to form a lithium transition metal composite oxide, and a method for producing a lithium transition metal composite oxide, which sequentially passes through the steps of crushing the obtained lithium transition metal composite oxide. During the wet pulverization, a part of the aqueous slurry was withdrawn from the pulverizer, passed through a device for sucking and removing magnetic powder by magnetic force, and then returned to the pulverizer. Removing the magnetic powder. A step of wet-pulverizing an aqueous slurry containing at least a transition metal compound selected from the group consisting of a manganese compound, a nickel compound and a cobalt compound; a step of spray-drying the wet-pulverized aqueous slurry to obtain a powder; Production of lithium transition metal composite oxide through successive steps of mixing lithium compound into sintering and firing to obtain lithium transition metal composite oxide, and sequentially crushing the obtained lithium transition metal composite oxide In the method, a part of the aqueous slurry is withdrawn from the crushing device during the wet crushing, passed through a device for sucking and removing magnetic powder by magnetic force, and then returned to the crushing device, and then subjected to a circulating operation, whereby the aqueous slurry is added to the aqueous slurry. A method characterized in that mixed magnetic powder is removed. 9. The method according to claim 7, wherein the aqueous slurry is cooled during the circulation operation. The method according to any one of claims 5 to 9, wherein the aqueous slurry is passed twice or more through a device for sucking and removing magnetic powder by magnetic force. The method according to any one of claims 5 to 9, wherein the aqueous slurry is passed through a device for sucking and removing magnetic powder by magnetic force 2 to 20 times. The method according to any one of claims 5 to 11, wherein the device for sucking and removing magnetic powder by a magnetic force is a magnetic powder removing device provided with a magnetic matrix. The aqueous slurry to be subjected to wet grinding is a metal selected from the group consisting of boron, aluminum, tin, copper, titanium, zinc, magnesium, gallium, calcium, silicon, vanadium, zirconium, antimony, ruthenium, lead, hafnium and tantalum. The method according to any one of claims 1 to 12, further comprising a compound. The method according to any one of claims 1 to 13, wherein a ratio of the metal compound in the aqueous slurry to be subjected to the wet pulverization is 10% by weight or more and 50% by weight or less. The method according to any one of claims 1 to 14, wherein the wet pulverization is performed until the average particle size of the metal compound in the aqueous slurry becomes 2 µm or less.

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