JP4066472B2 - Plate-like nickel hydroxide particles, method for producing the same, and method for producing lithium / nickel composite oxide particles using the same as a raw material - Google Patents
Plate-like nickel hydroxide particles, method for producing the same, and method for producing lithium / nickel composite oxide particles using the same as a raw material Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は、リチウムイオン二次電池の正極活物質であるリチウム・ニッケル複合酸化物（ニッケル酸リチウム）の原料として好適に用いることができる板状水酸化ニッケル粒子、その製造方法及びこれを原料として用いるリチウム・ニッケル複合酸化物粒子の製造方法に関する。
【０００２】
【従来の技術】
近年の携帯型電子機器の普及に伴い、高エネルギー密度で且つ高電圧使用の可能なリチウムイオン二次電池が注目を集めている。リチウムイオン二次電池の正極活物質としては、従来、コバルト酸リチウム、マンガン酸リチウム又はニッケル酸リチウム等の複合酸化物が知られている。このうち、コバルト酸リチウムは、原材料であるコバルトの産地が限定されていて、その安定供給が困難であるうえに、非常に高価であるという問題がある。一方、マンガン酸リチウムは、材料コストは比較的低く抑えることができるものの、コバルト酸リチウムを用いた場合ほどの高エネルギー密度が得られない問題がある。これに対して、ニッケル酸リチウムは、ニッケル原料が資源的に豊富であり、また、上記の二つに比べて、良好な容量特性を有し、しかも、最も大きいエネルギー密度を実現できる点で有望視されている。
【０００３】
ニッケル酸リチウムは、リチウム塩とニッケル化合物とを混合し、空気又は酸素気流中、通常、６００〜１０００℃の温度にて焼成することによって得られるが、焼成条件の微妙な相違によって、得られる複合酸化物におけるＬｉ／Ｎｉ比が変動し、リチウムとニッケルが結晶中の各々の層で不規則に配列するという製造上の困難さがある。この困難さを緩和するために、原料のニッケル化合物には、従来、主として、水酸化ニッケルが用いられている。
【０００４】
この水酸化ニッケル（Ｎｉ（ＯＨ）２）はＣｄＩ２型構造を有しており、ニッケル酸リチウム（ＬｉＮｉＯ２）と構造的な関連を有する。即ち、ニッケル酸リチウムの層面である（００３）面の間隔（＝ｃ／３）と水酸化ニッケルのニッケル層（００１）面の間隔が非常に近い。これは、ニッケル層及び酸素層の配列を乱すことなく、リチウムイオンを結晶の内部に導入できることを示唆するものであり、このことによって、ニッケル酸リチウムの製造の困難さを緩和することができる。更に、加うるに、原料である水酸化ニッケルの形状も、生成するニッケル酸リチウムにほぼ引き継がれることとなる。
【０００５】
かかる水酸化ニッケルの製造方法としては、ニッケル塩の水溶液にアンモニアを加えて、ニッケル−アンモニア錯塩とし、次いで、これに苛性アルカリを加えて、水酸化ニッケルを生成させる方法（特開昭５６−１４３６７１号公報）、ニッケル塩の水溶液を苛性アルカリを用いて同一の槽内で連続中和を行なって、取り出す方法（特開昭６３−１６５５５号公報）や、更に、アンモニアを連続添加する方法（特公平４−６８２４９号公報）等が知られている。
【０００６】
しかし、これらの方法で得られる水酸化ニッケルは、微細な一次粒子が強く凝集した粒状（球状）の粒子であり、このような凝集体は、その粒径は大きいものの、これを構成する一次粒子の粒径は小さい。かくして、従来の水酸化ニッケルは、結晶性の低い比表面積の大きい粒状（球状）の粒子である。そして、このような水酸化ニッケル粒子を用いて得られるニッケル酸リチウム粒子は、製造工程における焼成によって、一次粒子の若干の成長はあるものの、原料である水酸化ニッケル粒子の形状を強く残しており、通常、粒径が１μｍ以下の微細粒子よりなる球状の凝集粒子であり、一次粒子径が１μｍ以上の分散粒子を得ることは困難である。
【０００７】
ところで、リチウムイオン二次電池には、可燃性の非水電解液が用いられているので、何らかの原因で電池の温度が上昇したとき、これが契機となって発熱し、更に電池温度が上昇するという悪循環に陥り、場合によっては、発火、爆発という事態に陥りかねず、そこで、従来、自己発熱を抑える努力がなされている。正極においては、基本的な電池系では、正極電位より高い分解電圧を有する電解液が選択されるので、通常の状態では、反応は起こらない。しかし、何らかの原因によって、充電時に所定以上の電気量の電流が流れて、過充電状態になると、正極電位が上昇し、電解液が酸化され、発熱が起こる。この際、従来の微細な一次粒子からなる正極活物質を用いた正極では、このような酸化反応に対する活性が高く、酸化反応を速めてしまうという欠点を有している。
【０００８】
また、リチウムイオン二次電池では、充電時には、正極活物質であるリチウム複合酸化物からリチウムが脱ドープすることによって、結晶格子が収縮し、反対に、放電時には、リチウムがドープすることによって、結晶格子が膨張し、このため、リチウムイオン二次電池が充放電を繰り返す過程において、結晶格子の収縮、膨張が繰り返される結果、正極活物質の微粉化が起こり、容量の低下が引き起こされる。この正極活物質の微粉化もまた、一次粒子の小さい活物質ほど、起こりやすいことが知られている（特開平８−６９７９０号公報、特開平５−１５１９９８号公報等）。
【０００９】
そこで、従来、前述したように、コバルト酸リチウム、マンガン酸リチウム、ニッケル酸リチウム等の複合酸化物をリチウムイオン二次電池の正極活物質として用いる非水電解質リチウムイオン二次電池において、例えば、コバルト酸リチウムの場合、充放電サイクルの繰返しに伴う容量低下を少なくするために、上記複合酸化物が２〜１０μｍの平均粒径（５０％）を有することが保存特性や出力特性にすぐれる電池を得るために望ましいことが指摘されている（特開平５−９４８２２号公報）。また、ニッケル酸リチウムやニッケル、コバルト等の複合酸化物が１０％累積径が３〜１５μｍ、５０％累積径が８〜３５μｍ、９０％累積径が３０〜８０μｍであるような粒度分布を有するとき、高温環境下で充放電サイクルを繰り返したときも、容量低下が起こり難いことが指摘されている（特開平５−１５１９９８号公報）。更に、マンガン酸リチウムの場合には、平均粒径が３０〜１００μｍの範囲にあることが望ましいと指摘されている（特開平５−２８３０７４号公報）。
【００１０】
また、リチウム・マンガン複合酸化物からなる正極活物質を用いる非水電解質二次電池において、リチウム・マンガン複合酸化物の比表面積が０．０５〜５．０ｍ２／ｇの範囲にあるとき、サイクル特性にすぐれた電池を得ることができるとも指摘されている（特開平８−６９７９０号公報）。
【００１１】
【発明が解決しようとする課題】
本発明は、従来のリチウムイオン二次電池における上述したような事情に鑑み、特に、リチウムイオン二次電池における正極活物質における上述したような問題を解決するためになされたものであって、リチウムイオン二次電池の正極活物質の製造に好適に用いることができる一次粒子径の大きい板状の水酸化ニッケル粒子、その製造方法及びそのような水酸化ニッケル粒子を出発原料として用いるリチウム・ニッケル複合酸化物の製造方法を提供することを目的とする。
【００１２】
【課題を解決するための手段】
本発明によれば、一次粒子の平均長軸径が１〜５０μｍの範囲にあり、平均厚みが０．１〜１０μｍの範囲にあると共に、Ｎ２−ＢＥＴ法による比表面積が０．１〜５ｍ２／ｇの範囲にある板状水酸化ニッケル粒子が提供される。
【００１３】
また、本発明によれば、不定形又は粒状（球状）水酸化ニッケル粒子又はニッケル塩をアンモニア、水酸化アルカリ及びアンモニウム塩の水溶液中、１２０〜３５０℃の範囲の温度にて加熱することによる上記水酸化ニッケル粒子の製造方法が提供される。
【００１４】
更に、本発明によれば、上記板状水酸化ニッケル粒子をリチウム化合物と混合し、酸化性雰囲気下に６００〜１０００℃の範囲の温度で焼成することによるリチウム酸ニッケル粒子の製造方法が提供される。
【００１５】
【発明の実施の形態】
本発明による板状水酸化ニッケル粒子は、一次粒子の平均長軸径が１〜５０μｍの範囲にあり、平均厚みが０．１〜１０μｍの範囲にあると共に、Ｎ２−ＢＥＴ法による比表面積が０．１〜５ｍ２／ｇの範囲にある。
【００１６】
板状水酸化ニッケル粒子の一次粒子の平均長軸径が１μｍよりも小さいか、又は平均厚みが０．１μｍよりも小さいときは、これを出発原料としてリチウム・ニッケル複合酸化物粒子を製造するとき、得られるリチウム・ニッケル複合酸化物粒子は、その粒径が小さく、リチウムイオン二次電池の正極活物質として用いた場合、過充電時の酸化反応の速度が大きすぎるので、好ましくなく、また、充放電の繰返しによって、粒子の微粉化が起こりやすく、容量低下の要因となる点からも好ましくない。
【００１７】
しかしながら、板状水酸化ニッケル粒子の一次粒子の平均長軸径が５０μｍよりも大きいか、又は平均厚みが１０μｍよりも大きいときは、これを出発原料としてリチウム・ニッケル複合酸化物を製造すれば、得られるリチウム・ニッケル複合酸化物は、その粒径が大きく、従って、このような複合酸化物粒子を活物質として、導電剤や結着剤等と混練し、支持体上に塗布した形態で用いる際に、支持体を破損したり、負極やセパレータと共に巻き込む際にセパレータを傷付けて、ショートの原因ともなる。また、電池特性としても、高レート特性、即ち、放電電流を大きくし、短時間で放電した場合の放電容量の低下が大きいので好ましくない。このように、水酸化ニッケル粒子が上記範囲の大きさを有しないときは、これより得られるリチウム・ニッケル複合酸化物からなる正極活物質を備えた非水電解液リチウムイオン二次電池は、サイクル特性に劣るものとなるか、又は塗布性能やレート特性に劣るものとなる。
【００１８】
板状水酸化ニッケル粒子のＮ２−ＢＥＴ法による比表面積が０．１〜５ｍ２／ｇの範囲内にないときも、同様に、このような水酸化ニッケルからのリチウム・ニッケル複合酸化物からなる正極活物質を備えた非水電解質リチウムイオン二次電池は、サイクル特性に劣るものとなるかか、又は塗布性能やレート特性に劣るものとなる。
【００１９】
更に、本発明による板状水酸化ニッケル粒子は、平均長軸径／平均厚みで規定される平均板状比が２〜１０の範囲にあることが好ましい。
【００２０】
このような本発明による板状水酸化ニッケル粒子は、従来より知られている水酸化ニッケル粒子、即ち、不定形又は粒状（球状）の水酸化ニッケル粒子か、又は適宜のニッケル塩をアンモニア、水酸化アルカリ及びアンモニウム塩の水溶液中、１２０℃以上の温度にて加熱することによって得ることができる。ここに、上記ニッケル塩としては、例えば、硝酸ニッケル、硫酸ニッケル、塩化ニッケル、酢酸ニッケル、シュウ酸ニッケル等を用いることができるが、特に、硝酸ニッケルが好ましく用いられる。水酸化アルカリとしては、例えば、水酸化ナトリウム、水酸化カリウム、水酸化リチウム等が好ましく用いられる。上記アンモニウム塩としては、例えば、硫酸アンモニウム、硝酸アンモニウム、シュウ酸アンモニウム等が好ましく用いられる。
【００２１】
本発明による板状水酸化ニッケル粒子の製造の一つの好ましい態様として、例えば、前述したように、市販の粒状（球状）や不定形の水酸化ニッケル粒子をアンモニアのほか、上記水酸化アルカリとアンモニウム塩とを含む水溶液中、上記温度で加熱することによって得ることができる。このように、小さい一次粒子からなる粒状（球状）や不定形の水酸化ニッケル粒子をこのような方法によって水溶液とし、加熱すれば、このような水酸化ニッケル粒子が再溶解と再析出を繰り返すことによって、微細粒子が消失すると共に、粒径が大きく、且つ、板状の一次粒子への成長が起こるものとみられる。
【００２２】
このようにして、本発明による板状水酸化ニッケル粒子を製造する場合、通常、水酸化アルカリ、アンモニア及びアンモニウム塩は、それぞれ水酸化ニッケルに対して０．１当量以上用いられる。また、アンモニア水、水酸化アルカリ及びアンモニウム塩の量を適宜に選ぶことによって、厚みの増大した大きい粒径を有するほぼ粒状の粒子も得ることができる。
【００２３】
また、別の好ましい態様の一つとして、予め、反応容器中に水、水酸化アルカリ、アンモニア水及びアンモニウム塩水溶液の少なくとも１つを仕込み、温度を１２０℃以上に維持しつつ、この反応容器中にニッケル塩水溶液と共に、アンモニア水、水酸化アルカリ水溶液及びアンモニウム塩水溶液の少なくとも１つをそれぞれ連続的に圧入して、これらを１２０℃以上の温度で直接反応させてもよい。
【００２４】
このような方法においては、水酸化アルカリ、アンモニア及びアンモニウム塩は、それぞれ水酸化ニッケルに対して０．１当量以上で、且つ、合計で２当量以上用いられる。このような方法によれば、初期に生成した水酸化ニッケルの微細な核が系中で速やかに再溶解し、再析出し、数を減じるために、粒径の大きい板状の一次粒子が生成するものとみられる。この方法においては、必要に応じて、反応生成物を連続的に又は間欠的に反応容器から取り出してもよい。
【００２５】
上記加熱温度又は反応温度の上限は、特に、限定されるものではないが、温度を高くすれば、水蒸気圧も高くなり、反応容器の耐圧性を保つために、装置コストが高くなる問題が生じる。従って、加熱又は反応温度は、通常、３５０℃以下でよい。加熱又は反応温度が１２０℃よりも低いときは、従来より知られているような粒状（球状）の凝集粒子や微細な粒状の粒子が生成するのみであって、本発明による大きい板状の一次粒子を得ることができない。また、上記加熱又は反応の時間は、加熱又は反応温度によって異なるが、通常、数分から数十日の範囲である。
【００２６】
反応終了後、得られた混合物を冷却し、濾過等の分離方法を用いて固体を分離し、十分に水洗し、乾燥すれば、目的とする本発明による大きい板状の水酸化ニッケル粒子を得ることができる。
【００２７】
更に、本発明によれば、水溶性ニッケル塩、好ましくは、硝酸ニッケルと共にコバルト塩、マンガン塩、鉄塩及びバナジウム塩のうちの１種又は２種以上を含む水溶液を用いて、前述したようにして、ニッケルと共にこれら元素を含み、一次粒子の平均長軸径が１〜５０μｍの範囲にあり、平均厚みが０．１〜１０μｍの範囲にあると共に、Ｎ２−ＢＥＴ法による比表面積が０．１〜５ｍ２／ｇの範囲にある板状水酸化ニッケル粒子を得ることができる。
【００２８】
但し、このように、Ｃｏ、Ｍｎ、Ｆｅ及びＶよりなる群から選ばれる少なくとも１種の元素を含む板状水酸化ニッケル粒子を製造する場合、（Ｃｏ、Ｍｎ、Ｆｅ及びＶ）／Ｎｉ原子比が０．４以下であることが好ましい。この原子比が０．４を越えるときは、このような水酸化ニッケル粒子を用いてリチウムとの複合酸化物を製造し、これを正極活物質として用いても、容量の大きいリチウムイオン二次電池を得ることができない。
【００２９】
本発明による板状水酸化ニッケル粒子を用いることによって、一次粒子の大きいリチウムニッケル複合酸化物を容易に得ることができる。即ち、本発明による板状水酸化ニッケル粒子とリチウム化合物とを乾式又は湿式混合し、空気や酸素等の酸化性雰囲気中、６００〜１０００℃の温度にて焼成することによって得ることができる。上記リチウム化合物としては、例えば、炭酸リチウム、水酸化リチウム一水塩等が好ましく用いられる。反応温度が６００℃よりも低いときは、リチウムが十分に複合酸化物の内部までドープされず、他方、１０００℃を越えるときは、リチウムが揮散し、リチウム／ニッケル比を変動させ、また、不純物としての酸化ニッケルの生成等が起こるので、好ましくない。
【００３０】
本発明によれば、このような方法によって、原料である板状水酸化ニッケル粒子の形状を受け継ぎ、一次粒子径の大きいリチウムニッケル複合酸化物を容易に得ることができる。
【００３１】
本発明においては、上記リチウムニッケル複合酸化物と前記水酸化ニッケルは、これらを正極活物質原料とする電池の特性を向上させるために、従来より知られているように、マンガン、コバルト、アルミニウム、ホウ素、マグネシウム等の元素を含有させてもよい。
【００３２】
【実施例】
以下に実施例を挙げて本発明を説明するが、本発明はこれら実施例により何ら限定されるものではない。以下において、％は、特に別の記載がなければ、重量％を意味する。また、以下の実施例１〜７及び比較例１〜３において得た水酸化ニッケルの粒子について、その平均長軸径、平均厚み、平均板状比及び比表面積を表１に示す。
【００３３】
（水酸化ニッケル粒子の製造）
実施例１
１９．６％水酸化ナトリウム水溶液２９２ｇ、２２％アンモニア水溶液３８ｇ及び硝酸アンモニウム２３０ｇに純水を加え、容積を７００ｍＬとし、この水溶液を３Ｌ容量のオートクレーブ中に移した。この水溶液を２５０℃に加熱した後、オートクレーブ中に、攪拌下、２３．６％硝酸ニッケル水溶液を４２ｇ／時、１９．６％水酸化ナトリウム水溶液を２４ｇ／時の割合で連続的に圧入しつつ、２５０℃の温度で２２時間反応させた。反応終了後、オートクレーブ内を冷却し、反応混合物を濾過、水洗し、この後、１０５℃で一晩乾燥させて、水酸化ニッケル粉末６８ｇを得た。
【００３４】
このようにして得た水酸化ニッケルの粒子の走査型電子顕微鏡写真を図１に示す。また、試料台を傾けて撮影した水酸化ニッケル粒子の厚み方向の走査型電子顕微鏡写真の一例を図２に示す。これらの走査型電子顕微鏡写真から一次粒子の形状及び大きさを測定した（以下の実施例及び比較例において用いる同様に測定した。）結果、一次粒子は、板状であって、平均長軸径６．２μｍ、平均厚み２．０μｍであり、Ｎ２−ＢＥＴ法による比表面積は０．９ｍ２／ｇであった。
【００３５】
実施例２
１９．６％水酸化ナトリウム水溶液２９２ｇ、２２％アンモニア水溶液３８ｇ及び硝酸アンモニウム３８ｇに純水を加え、容積を７００ｍＬとした。この水溶液を３Ｌ容量のオートクレーブ中に移した。この水溶液を２５０℃に加熱した後、オートクレーブ中に、攪拌下、２３．６％硝酸ニッケル水溶液を４２ｇ／時、１９．６％水酸化ナトリウム水溶液を２４ｇ／時の割合で連続的に圧入しつつ、２５０℃の温度で２０時間反応させた。
【００３６】
次いで、オートクレーブ中に、２３．６％硝酸ニッケル水溶液を４２ｇ／時、１９．６％水酸化ナトリウム水溶液を２４ｇ／時、２２％アンモニア水１００ｇと硝酸アンモニウム１０２ｇを水２９０ｇに溶解した水溶液を６ｇ／時の割合で連続的に圧入しつつ、且つ、反応生成物を６０ｍＬ／時の割合で連続的に取出しつつ、２５０℃の温度で８０時間反応させた。その後、反応混合物を冷却し、オートクレーブから取り出し、以下、実施例１と同様に処理して、水酸化ニッケル粉末９７ｇを得た。図３に得られた水酸化ニッケルの粒子の走査型電子顕微鏡写真を示す。また、図４にＣｕ−Ｋα線を用いて測定したＸ線回折図を示す。得られた粒子が水酸化ニッケルであることは、このＸ線回折図によって確認した。
【００３７】
得られた水酸化ニッケルの一次粒子は、板状であって、平均長軸径３．２μｍ、平均厚み０．５４μｍであり、Ｎ２−ＢＥＴ法による比表面積は１．７ｍ２／ｇであった。
【００３８】
実施例３
３Ｌ容量のオートクレーブ内に純水５００ｍＬを仕込み、２５０℃に加熱した後、２３．６％硝酸ニッケル水溶液を４２ｇ／時、１９．６％水酸化ナトリウム水溶液を２４ｇ／時、２２％アンモニア水１００ｇと硝酸アンモニウム１０２ｇを水２９０ｇに溶解した水溶液を６ｇ／時の割合で連続的に圧入しつつ、２５０℃の温度で２０時間反応させた。反応終了後、実施例１と同様にし処理して、水酸化ニッケル粉末１００ｇを得た。
【００３９】
得られた水酸化ニッケルの一次粒子は、板状であって、平均長軸径３．９μｍ、平均厚み０．７１μｍであり、Ｎ２−ＢＥＴ法による比表面積は１．５ｍ２／ｇであった。
【００４０】
実施例４
実施例１において、硝酸アンモニウム３８ｇを用いると共に、２３．６％硝酸ニッケル水溶液に代えて、硝酸ニッケルの１５％を硝酸コバルトで置換した合計濃度２３．６％の硝酸ニッケルと硝酸コバルトの水溶液を４２ｇ／時で用いた以外は、実施例１と同様に処理して、コバルトを含む水酸化ニッケル粉末６０ｇを得た。図５に得られたコバルトを含む水酸化ニッケルの粒子の走査型電子顕微鏡写真を示す。
【００４１】
得られた水酸化ニッケルの一次粒子は、板状であって、平均長軸径１．１μｍ、平均厚み０．１８μｍであり、Ｎ２−ＢＥＴ法による比表面積は３．５ｍ２／ｇであった。また、蛍光Ｘ線分析の結果、ニッケル／コバルト重量比は０．８５／０．１５であった。
【００４２】
実施例５
２２％アンモニア水３８ｇと硝酸アンモニウム３２ｇに水を加え、溶解させて、容積を７００ｍＬとした。この水溶液を３Ｌ容量のオートクレーブ内に仕込み、２５０℃に加熱した後、オートクレーブ中に、攪拌下、２３．６％硝酸ニッケル水溶液を４２ｇ／時、１９．６％水酸化ナトリウム水溶液を２４ｇ／時の割合で連続的に圧入しつつ、２５０℃の温度で２２時間反応させた。反応終了後、実施例１と同様に処理して、水酸化ニッケル粉末７０ｇを得た。
【００４３】
得られた水酸化ニッケルの一次粒子は、板状であって、平均長軸径１．７μｍ、平均厚み０．３４μｍであり、Ｎ２−ＢＥＴ法による比表面積は３．４ｍ２／ｇであった。
【００４４】
比較例１
（従来の反応晶析法）
１２Ｌ容量のビーカーに純水１０Ｌを入れ、攪拌羽根にて攪拌しつつ、温度を４０℃に維持しつつ、これに１．６モル／Ｌの硝酸ニッケル水溶液を２９０ｍＬ／時、１３．３４モル／Ｌのアンモニア水を５２ｍＬ／時、８．５５モル／Ｌの水酸化ナトリウム水溶液を反応系のｐＨが１１〜１２となるよう調整しつつ（平均割合１６０ｍＬ／時）で、それぞれ連続的に加え、得られた反応混合物を連続的に取り出した。このようにして得られた反応生成物を純水にて洗浄し、その後、１０５℃にて一晩乾燥させて、水酸化ニッケル粉末を得た。この水酸化ニッケルの粒子の走査型電子顕微鏡写真を図６に示す。
【００４５】
得られた水酸化ニッケル粒子は、一次粒子径０．１μｍ以下の一次粒子が凝集した二次粒子径１０μｍの球状であって、Ｎ２−ＢＥＴ法による比表面積は３４．１ｍ２／ｇであった。
【００４６】
実施例６
比較例１にて得た球状の水酸化ニッケル粒子３８．９ｇと硫酸アンモニウム１１１ｇに純水を加えて、容積を１５０ｍＬとし、これを十分に攪拌した。これに２２％アンモニア水２６３ｇと１９．６％の苛性ソーダ溶液１７１ｇを加えた後、これを１Ｌ容量のオートクレーブ中に仕込み、２５０℃で２０時間加熱処理を行なった。反応終了後、反応混合物を冷却し、以下、実施例１と同様に処理して、水酸化ニッケル粉末５．５ｇを得た。この水酸化ニッケルの粒子の走査型電子顕微鏡写真を図７に示す。
【００４７】
得られた水酸化ニッケル粒子は、一次粒子径１．８μｍ、平均厚み０．７２μｍの板状であって、Ｎ２−ＢＥＴ法による比表面積は１．６ｍ２／ｇであった。
【００４８】
実施例７
ディスパー攪拌下、２３．６％硝酸ニッケル水溶液３２４ｇ中に１９．６％水酸化ナトリウム水溶液２７３ｇを加えて中和し、これに２２％アンモニア水１３．２ｇと硝酸アンモニウム８０．７ｇとを加え、更に、純水を加えて、全容積を６００ｍＬとした後、３０分間攪拌した。これを１Ｌ容量のオートクレーブ中に移し入れ、２５０℃で９６時間加熱処理を行なった。反応終了後、得られた反応混合物を実施例１と同様に処理して、水酸化ニッケル粉末を得た。
【００４９】
得られた水酸化ニッケル粒子は、一次粒子径１．０μｍ、平均厚み０．１４μｍの板状であって、Ｎ２−ＢＥＴ法による比表面積は４．４ｍ２／ｇであった。
【００５０】
比較例２
反応温度を９０℃とした以外は、実施例４と同様に反応を行なった。得られた水酸化ニッケルは、その走査型電子顕微鏡写真を図８に示すように、一次粒径０．２μｍ以下の微細な粒子であって、Ｎ２−ＢＥＴ法による比表面積は２０．１ｍ２／ｇであった。
【００５１】
比較例３
オートクレーブ中での反応温度を９０℃とした以外は、実施例７と同様に反応を行なって、水酸化ニッケルを一次粒径０．１μｍの微細な一次粒子からなる二次凝集粒子として得た。この水酸化ニッケル粒子のＮ２−ＢＥＴ法による比表面積は２１．５ｍ２／ｇであった。
【００５２】
【表１】
（リチウムニッケル複合酸化物の製造）
実施例８
実施例２にて得た水酸化ニッケル粉末３０ｇと自動乳鉢にて粉砕した水酸化リチウム一水塩１３．６ｇをポリエチレン製の袋に入れて、十分に混合した。このようにして得た混合物の１０ｇをアルミナ製るつぼに入れ、酸素雰囲気中、２００℃／時の割合で昇温した後、８００℃にて１０時間焼成した。この後、２００℃／時の割合で常温まで冷却して、リチウムニッケル複合酸化物粒子を得た。
【００５４】
このリチウムニッケル複合酸化物粒子の走査型電子顕微鏡写真を図９に示し、また、図１０にＣｕ−Ｋα線を用いて測定したＸ線回折図を示す。これより、得られたリチウムニッケル複合酸化物は、ニッケル酸リチウム単一相であることが確認された。得られた粒子がニッケル酸リチウムであることは、このＸ線回折図によって確認した。得られたリチウムニッケル複合酸化物の粒子は、一次粒子平均長軸径５μｍ、平均厚み０．５μｍであって、原料として用いた水酸化ニッケル粒子の形状を強く引き継いだ大きい粒径の板状粒子であった。
【００５５】
比較例４
比較例１にて得た水酸化ニッケル粉末を用いた以外は、実施例８と同様に反応を行なって、リチウムニッケル複合酸化物粒子を得た。この粒子の走査型電子顕微鏡写真を図１１に示すように、一次粒子の若干の成長はみられるものの、原料として用いた水酸化ニッケルの形状を強く引き継ぎ、表面に微細構造を有する球状の粒子であった。
【図面の簡単な説明】
【図１】は、実施例１にて得た水酸化ニッケル粒子の走査型電子顕微鏡写真（１０００倍）である。
【図２】は、実施例１にて得た水酸化ニッケル粒子の走査型電子顕微鏡写真の撮影時に試料台を傾けて撮影したものである（１０００倍）。
【図３】は、実施例２にて得た水酸化ニッケル粒子の走査型電子顕微鏡写真（５０００倍）である。
【図４】は、実施例２にて得た水酸化ニッケル粒子のＸ線回折図である。縦軸は、Ｘ線強度（ＣＰＳ）であり、横軸は回折角（２θ）である。
【図５】は、実施例４にて得た水酸化ニッケル粒子の走査型電子顕微鏡写真（１００００倍）である。
【図６】は、比較例１にて得た水酸化ニッケル粒子の走査型電子顕微鏡写真（５０００倍）である。
【図７】は、実施例６にて得た水酸化ニッケル粒子の走査型電子顕微鏡写真（５０００倍）である。
【図８】は、比較例２にて得た水酸化ニッケル粒子の走査型電子顕微鏡写真（１００００倍）である。
【図９】は、実施例８にて得たリチウム・ニツケル複合酸化物粒子の走査型電子顕微鏡写真（５０００倍）である。
【図１０】は、実施例８にて得たリチウム・ニツケル複合酸化物粒子のＸ線回折図である。
【図１１】は、比較例４にて得たリチウム・ニツケル複合酸化物粒子の走査型電子顕微鏡写真（５０００倍）である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to plate-like nickel hydroxide particles that can be suitably used as a raw material for a lithium-nickel composite oxide (lithium nickelate) that is a positive electrode active material of a lithium ion secondary battery, a method for producing the same, and a raw material for the same. The present invention relates to a method for producing lithium-nickel composite oxide particles to be used.
[0002]
[Prior art]
With the spread of portable electronic devices in recent years, a lithium ion secondary battery that can be used at a high energy density and a high voltage is attracting attention. Conventionally, composite oxides such as lithium cobaltate, lithium manganate, or lithium nickelate have been known as positive electrode active materials for lithium ion secondary batteries. Among these, lithium cobaltate has a problem that the production area of cobalt, which is a raw material, is limited, and its stable supply is difficult and it is very expensive. On the other hand, lithium manganate has a problem that although the material cost can be kept relatively low, the energy density as high as when lithium cobaltate is used cannot be obtained. On the other hand, lithium nickelate is promising because it has abundant nickel raw materials, has better capacity characteristics than the above two, and can achieve the highest energy density. Is being viewed.
[0003]
Lithium nickelate is obtained by mixing lithium salt and nickel compound and firing in air or oxygen stream, usually at a temperature of 600 to 1000 ° C., but the composite obtained by subtle differences in firing conditions There is a manufacturing difficulty that the Li / Ni ratio in the oxide fluctuates and lithium and nickel are irregularly arranged in each layer in the crystal. In order to alleviate this difficulty, nickel hydroxide is conventionally mainly used as a raw material nickel compound.
[0004]
This nickel hydroxide (Ni (OH) 2 ) Is CdI 2 A lithium nickelate (LiNiO) 2 ) And a structural link. That is, the distance between the (003) planes (= c / 3), which is the lithium nickelate layer surface, is very close to the distance between the nickel hydroxide (001) surfaces of nickel hydroxide. This suggests that lithium ions can be introduced into the crystal without disturbing the arrangement of the nickel layer and the oxygen layer, which can alleviate the difficulty in producing lithium nickelate. In addition, the shape of nickel hydroxide as a raw material is almost inherited by the produced lithium nickelate.
[0005]
As a method for producing such nickel hydroxide, ammonia is added to an aqueous solution of nickel salt to form a nickel-ammonia complex salt, and then caustic is added thereto to produce nickel hydroxide (Japanese Patent Laid-Open No. 56-143671). No.), a method of removing an aqueous solution of nickel salt by continuous neutralization using caustic in the same tank (Japanese Patent Laid-Open No. 63-16555), and a method of adding ammonia continuously (special feature) No. 4-68249) is known.
[0006]
However, the nickel hydroxide obtained by these methods is a granular (spherical) particle in which fine primary particles are strongly aggregated, and although such an aggregate has a large particle size, the primary particles constituting this The particle size of is small. Thus, conventional nickel hydroxide is granular (spherical) particles having low crystallinity and a large specific surface area. And the lithium nickelate particles obtained by using such nickel hydroxide particles strongly retain the shape of the nickel hydroxide particles as the raw material, although there is some growth of the primary particles by firing in the manufacturing process. Usually, it is difficult to obtain dispersed particles having spherical aggregates composed of fine particles having a particle size of 1 μm or less and having a primary particle size of 1 μm or more.
[0007]
By the way, since the flammable non-aqueous electrolyte is used for the lithium ion secondary battery, when the temperature of the battery rises for some reason, this causes the heat generation and further increases the battery temperature. There is a vicious circle, and in some cases, it can lead to a situation of ignition or explosion. Therefore, efforts have been made to suppress self-heating. In the positive electrode, in a basic battery system, an electrolyte having a decomposition voltage higher than the positive electrode potential is selected, so that no reaction occurs in a normal state. However, if for some reason, an electric current of a predetermined amount or more flows during charging and an overcharged state occurs, the positive electrode potential rises, the electrolyte is oxidized, and heat is generated. At this time, the positive electrode using the positive electrode active material made of conventional fine primary particles has a drawback that it has a high activity for such an oxidation reaction and accelerates the oxidation reaction.
[0008]
In addition, in a lithium ion secondary battery, when decharging, lithium is dedoped from a lithium composite oxide that is a positive electrode active material, so that the crystal lattice contracts. The lattice expands. For this reason, in the process in which the lithium ion secondary battery repeats charging and discharging, the crystal lattice is repeatedly contracted and expanded. As a result, the positive electrode active material is pulverized and the capacity is reduced. It is known that this positive electrode active material pulverization is also more likely to occur with an active material having smaller primary particles (JP-A-8-69790, JP-A-5-151998, etc.).
[0009]
Therefore, conventionally, as described above, in a non-aqueous electrolyte lithium ion secondary battery using a composite oxide such as lithium cobaltate, lithium manganate, lithium nickelate as a positive electrode active material of a lithium ion secondary battery, for example, cobalt In the case of lithium acid, in order to reduce the capacity drop due to repeated charge and discharge cycles, a battery having excellent storage characteristics and output characteristics that the composite oxide has an average particle size (50%) of 2 to 10 μm It is pointed out that it is desirable to obtain (JP-A-5-94822). Also, when the composite oxide such as lithium nickelate, nickel, and cobalt has a particle size distribution such that the 10% cumulative diameter is 3 to 15 μm, the 50% cumulative diameter is 8 to 35 μm, and the 90% cumulative diameter is 30 to 80 μm. In addition, it has been pointed out that capacity reduction is unlikely to occur even when a charge / discharge cycle is repeated in a high temperature environment (Japanese Patent Laid-Open No. 5-151998). Furthermore, in the case of lithium manganate, it has been pointed out that it is desirable that the average particle size be in the range of 30 to 100 μm (Japanese Patent Laid-Open No. H5-283074).
[0010]
Further, in the nonaqueous electrolyte secondary battery using the positive electrode active material made of lithium / manganese composite oxide, the specific surface area of the lithium / manganese composite oxide is 0.05 to 5.0 m. 2 It has also been pointed out that a battery having excellent cycle characteristics can be obtained when it is in the range of / g (JP-A-8-69790).
[0011]
[Problems to be solved by the invention]
The present invention has been made in order to solve the above-described problems in the positive electrode active material in a lithium ion secondary battery, in view of the above-described circumstances in a conventional lithium ion secondary battery, and Plate-like nickel hydroxide particles having a large primary particle size that can be suitably used for the production of a positive electrode active material for an ion secondary battery, a method for producing the same, and a lithium / nickel composite using such nickel hydroxide particles as a starting material An object is to provide a method for producing an oxide.
[0012]
[Means for Solving the Problems]
According to the present invention, the average major axis diameter of the primary particles is in the range of 1 to 50 μm, the average thickness is in the range of 0.1 to 10 μm, and N 2 -Specific surface area by BET method is 0.1-5m 2 Plate-like nickel hydroxide particles in the range of / g are provided.
[0013]
According to the present invention, the amorphous or granular (spherical) nickel hydroxide particles or nickel salt is heated in an aqueous solution of ammonia, alkali hydroxide and ammonium salt at a temperature in the range of 120 to 350 ° C. A method for producing nickel hydroxide particles is provided.
[0014]
Furthermore, according to the present invention, there is provided a method for producing nickel lithiate particles by mixing the plate-like nickel hydroxide particles with a lithium compound and firing at a temperature in the range of 600 to 1000 ° C. in an oxidizing atmosphere. The
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The plate-like nickel hydroxide particles according to the present invention have an average major axis diameter of primary particles in the range of 1 to 50 μm, an average thickness in the range of 0.1 to 10 μm, and N 2 -Specific surface area by BET method is 0.1-5m 2 / G.
[0016]
When the average major axis diameter of the primary particles of the plate-like nickel hydroxide particles is smaller than 1 μm or the average thickness is smaller than 0.1 μm, when producing lithium / nickel composite oxide particles using this as a starting material The obtained lithium / nickel composite oxide particles are not preferable because the particle size is small, and when used as the positive electrode active material of a lithium ion secondary battery, the rate of oxidation reaction during overcharge is too high. The repetition of charge / discharge is not preferable from the viewpoint that particles are easily pulverized and cause a decrease in capacity.
[0017]
However, when the average major axis diameter of the primary particles of the plate-like nickel hydroxide particles is larger than 50 μm or the average thickness is larger than 10 μm, if this is used as a starting material to produce a lithium / nickel composite oxide, The obtained lithium / nickel composite oxide has a large particle size. Therefore, such a composite oxide particle is used as an active material, kneaded with a conductive agent, a binder or the like, and used on a support. At that time, the support may be damaged, or the separator may be damaged when it is wound together with the negative electrode or the separator, causing a short circuit. Further, the battery characteristics are not preferable because of high rate characteristics, that is, a large decrease in discharge capacity when the discharge current is increased and discharged in a short time. Thus, when the nickel hydroxide particles do not have a size in the above range, a non-aqueous electrolyte lithium ion secondary battery including a positive electrode active material made of a lithium-nickel composite oxide obtained from the cycle is cycled. The properties are inferior, or the coating performance and rate properties are inferior.
[0018]
N of plate-like nickel hydroxide particles 2 -Specific surface area by BET method is 0.1-5m 2 Similarly, a non-aqueous electrolyte lithium ion secondary battery including a positive electrode active material composed of a lithium / nickel composite oxide from nickel hydroxide is inferior in cycle characteristics even when not in the range of / g. Or poor coating performance and rate characteristics.
[0019]
Furthermore, the plate-like nickel hydroxide particles according to the present invention preferably have an average plate-like ratio in the range of 2 to 10 defined by the average major axis diameter / average thickness.
[0020]
Such plate-like nickel hydroxide particles according to the present invention are conventionally known nickel hydroxide particles, that is, amorphous or granular (spherical) nickel hydroxide particles, or an appropriate nickel salt made of ammonia, water. It can obtain by heating at the temperature of 120 degreeC or more in the aqueous solution of an alkali oxide and ammonium salt. Here, as the nickel salt, for example, nickel nitrate, nickel sulfate, nickel chloride, nickel acetate, nickel oxalate and the like can be used, and nickel nitrate is particularly preferably used. As the alkali hydroxide, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide and the like are preferably used. As said ammonium salt, ammonium sulfate, ammonium nitrate, ammonium oxalate etc. are used preferably, for example.
[0021]
As one preferred embodiment of the production of the plate-like nickel hydroxide particles according to the present invention, for example, as described above, commercially available granular (spherical) or amorphous nickel hydroxide particles are used in addition to ammonia, and the alkali hydroxide and ammonium. It can obtain by heating at the said temperature in the aqueous solution containing a salt. In this way, granular (spherical) or amorphous nickel hydroxide particles consisting of small primary particles are made into an aqueous solution by such a method, and when heated, such nickel hydroxide particles are repeatedly dissolved and reprecipitated. As a result, the fine particles disappear, the particle size is large, and the growth to plate-like primary particles occurs.
[0022]
Thus, when producing the plate-like nickel hydroxide particles according to the present invention, the alkali hydroxide, ammonia and ammonium salt are usually used in an amount of 0.1 equivalent or more with respect to nickel hydroxide. In addition, by selecting the amounts of aqueous ammonia, alkali hydroxide and ammonium salt as appropriate, almost granular particles having a large particle size with increased thickness can be obtained.
[0023]
As another preferred embodiment, at least one of water, alkali hydroxide, aqueous ammonia, and an aqueous ammonium salt solution is previously charged in the reaction vessel, and the temperature is maintained at 120 ° C. or higher. In addition to the nickel salt aqueous solution, at least one of ammonia water, alkali hydroxide aqueous solution and ammonium salt aqueous solution may be continuously injected, and these may be directly reacted at a temperature of 120 ° C. or higher.
[0024]
In such a method, the alkali hydroxide, ammonia and ammonium salt are used in an amount of 0.1 equivalents or more and 2 equivalents or more in total with respect to nickel hydroxide. According to such a method, the fine nuclei of nickel hydroxide generated in the early stage rapidly re-dissolve in the system, re-precipitate, and reduce the number so that plate-like primary particles having a large particle size are generated. It seems to do. In this method, the reaction product may be removed from the reaction vessel continuously or intermittently as necessary.
[0025]
The upper limit of the heating temperature or the reaction temperature is not particularly limited, but if the temperature is increased, the water vapor pressure also increases, and there is a problem that the apparatus cost increases in order to maintain the pressure resistance of the reaction vessel. . Accordingly, the heating or reaction temperature is usually 350 ° C. or lower. When the heating or reaction temperature is lower than 120 ° C., only the granular (spherical) agglomerated particles and fine granular particles as conventionally known are produced, and the large plate-like primary according to the present invention is produced. Unable to get particles. The heating or reaction time varies depending on the heating or reaction temperature, but is usually in the range of several minutes to several tens of days.
[0026]
After completion of the reaction, the obtained mixture is cooled, the solid is separated using a separation method such as filtration, sufficiently washed with water, and dried to obtain the desired large plate-like nickel hydroxide particles according to the present invention. be able to.
[0027]
Furthermore, according to the present invention, as described above, a water-soluble nickel salt, preferably an aqueous solution containing one or more of cobalt, manganese, iron and vanadium with nickel nitrate is used. In addition, these elements are included together with nickel, the average major axis diameter of the primary particles is in the range of 1 to 50 μm, the average thickness is in the range of 0.1 to 10 μm, and N 2 -Specific surface area by BET method is 0.1-5m 2 Plate-like nickel hydroxide particles in the range of / g can be obtained.
[0028]
However, when producing plate-like nickel hydroxide particles containing at least one element selected from the group consisting of Co, Mn, Fe and V in this way, (Co, Mn, Fe and V) / Ni atomic ratio Is preferably 0.4 or less. When this atomic ratio exceeds 0.4, a lithium-ion secondary battery having a large capacity is produced even if a composite oxide with lithium is produced using such nickel hydroxide particles and this is used as a positive electrode active material. Can't get.
[0029]
By using the plate-like nickel hydroxide particles according to the present invention, a lithium nickel composite oxide having large primary particles can be easily obtained. That is, it can be obtained by dry or wet mixing the plate-like nickel hydroxide particles and the lithium compound according to the present invention, and firing at a temperature of 600 to 1000 ° C. in an oxidizing atmosphere such as air or oxygen. As the lithium compound, for example, lithium carbonate, lithium hydroxide monohydrate and the like are preferably used. When the reaction temperature is lower than 600 ° C., lithium is not sufficiently doped into the composite oxide. On the other hand, when it exceeds 1000 ° C., lithium is volatilized, the lithium / nickel ratio is changed, and impurities The formation of nickel oxide or the like is not preferable.
[0030]
According to the present invention, a lithium nickel composite oxide having a large primary particle diameter can be easily obtained by inheriting the shape of the plate-like nickel hydroxide particles as a raw material by such a method.
[0031]
In the present invention, the lithium nickel composite oxide and the nickel hydroxide are manganese, cobalt, aluminum, as conventionally known, in order to improve the characteristics of the battery using these as a positive electrode active material raw material. Elements such as boron and magnesium may be contained.
[0032]
【Example】
EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the following, “%” means “% by weight” unless otherwise specified. Moreover, the following Examples 1-7 as well as Comparative Examples 1 to 3 Table 1 shows the average major axis diameter, average thickness, average plate ratio, and specific surface area of the nickel hydroxide particles obtained in 1.
[0033]
(Manufacture of nickel hydroxide particles)
Example 1
Pure water was added to 292 g of 19.6% sodium hydroxide aqueous solution, 38 g of 22% ammonia aqueous solution and 230 g of ammonium nitrate to make the volume 700 mL, and this aqueous solution was transferred into a 3 L autoclave. After this aqueous solution was heated to 250 ° C., it was continuously pressed into the autoclave at a rate of 23.6% nickel nitrate aqueous solution 42 g / hour and 19.6% sodium hydroxide aqueous solution 24 g / hour with stirring. And reacted at a temperature of 250 ° C. for 22 hours. After completion of the reaction, the inside of the autoclave was cooled, the reaction mixture was filtered and washed with water, and then dried at 105 ° C. overnight to obtain 68 g of nickel hydroxide powder.
[0034]
A scanning electron micrograph of the nickel hydroxide particles thus obtained is shown in FIG. FIG. 2 shows an example of a scanning electron micrograph in the thickness direction of nickel hydroxide particles photographed by tilting the sample stage. The shape and size of the primary particles were measured from these scanning electron micrographs (measured in the same manner as used in the following Examples and Comparative Examples). As a result, the primary particles were plate-like and had an average major axis diameter. 6.2 μm, average thickness 2.0 μm, N 2 -Specific surface area by BET method is 0.9m 2 / G.
[0035]
Example 2
Pure water was added to 292 g of 19.6% aqueous sodium hydroxide solution, 38 g of 22% aqueous ammonia solution and 38 g of ammonium nitrate to make the volume 700 mL. This aqueous solution was transferred into a 3 L autoclave. After this aqueous solution was heated to 250 ° C., it was continuously pressed into the autoclave at a rate of 23.6% nickel nitrate aqueous solution 42 g / hour and 19.6% sodium hydroxide aqueous solution 24 g / hour with stirring. And reacted at a temperature of 250 ° C. for 20 hours.
[0036]
Next, in an autoclave, 23.6% nickel nitrate aqueous solution 42 g / hour, 19.6% sodium hydroxide aqueous solution 24 g / hour, 22% aqueous ammonia 100 g and ammonium nitrate 102 g dissolved in 290 g water 6 g / hour The reaction product was allowed to react at a temperature of 250 ° C. for 80 hours while continuously injecting at a rate of 60 ° C. and continuously taking out the reaction product at a rate of 60 mL / hour. Thereafter, the reaction mixture was cooled, taken out from the autoclave, and treated in the same manner as in Example 1 to obtain 97 g of nickel hydroxide powder. FIG. 3 shows a scanning electron micrograph of the nickel hydroxide particles obtained. FIG. 4 shows an X-ray diffraction pattern measured using Cu—Kα rays. It was confirmed by this X-ray diffraction pattern that the obtained particles were nickel hydroxide.
[0037]
The obtained primary particles of nickel hydroxide have a plate shape, an average major axis diameter of 3.2 μm, an average thickness of 0.54 μm, and N 2 -Specific surface area by BET method is 1.7m 2 / G.
[0038]
Example 3
After charging 500 mL of pure water into a 3 L autoclave and heating to 250 ° C., 23.6% aqueous nickel nitrate solution was 42 g / hour, 19.6% aqueous sodium hydroxide solution was 24 g / hour, and 22% aqueous ammonia was 100 g. An aqueous solution in which 102 g of ammonium nitrate was dissolved in 290 g of water was continuously injected at a rate of 6 g / hour, and reacted at a temperature of 250 ° C. for 20 hours. After completion of the reaction, the same treatment as in Example 1 was performed to obtain 100 g of nickel hydroxide powder.
[0039]
The obtained primary particles of nickel hydroxide have a plate shape, an average major axis diameter of 3.9 μm, an average thickness of 0.71 μm, and N 2 -Specific surface area by BET method is 1.5m 2 / G.
[0040]
Example 4
In Example 1, 38 g of ammonium nitrate was used, and instead of the 23.6% nickel nitrate aqueous solution, an aqueous solution of nickel nitrate and cobalt nitrate having a total concentration of 23.6% in which 15% of nickel nitrate was replaced with cobalt nitrate was 42 g / Except for the occasional use, the same treatment as in Example 1 was performed to obtain 60 g of nickel hydroxide powder containing cobalt. FIG. 5 shows a scanning electron micrograph of the nickel hydroxide particles containing cobalt obtained.
[0041]
The obtained primary particles of nickel hydroxide have a plate shape, an average major axis diameter of 1.1 μm, an average thickness of 0.18 μm, and N 2 -Specific surface area by BET method is 3.5m 2 / G. As a result of fluorescent X-ray analysis, the nickel / cobalt weight ratio was 0.85 / 0.15.
[0042]
Example 5
Water was added to 38 g of 22% ammonia water and 32 g of ammonium nitrate and dissolved to make the volume 700 mL. This aqueous solution was charged into a 3 L-volume autoclave and heated to 250 ° C., and then the autoclave was stirred with 23.6% nickel nitrate aqueous solution at 42 g / hour and 19.6% sodium hydroxide aqueous solution at 24 g / hour. The reaction was carried out at a temperature of 250 ° C. for 22 hours while continuously pressing at a rate. After completion of the reaction, the same treatment as in Example 1 was performed to obtain 70 g of nickel hydroxide powder.
[0043]
The obtained primary particles of nickel hydroxide have a plate shape, an average major axis diameter of 1.7 μm, an average thickness of 0.34 μm, and N 2 -Specific surface area by BET method is 3.4m 2 / G.
[0044]
Comparative Example 1
(Conventional reactive crystallization method)
10 L of pure water was put into a 12 L capacity beaker and the temperature was maintained at 40 ° C. while stirring with a stirring blade, and 1.6 mol / L nickel nitrate aqueous solution was added to this at 290 mL / hour, 13.34 mol / hour. While adjusting the pH of the reaction system to 11 to 12 (average rate 160 mL / hr), 52 mL / hr of aqueous ammonia and 8.55 mol / L of sodium hydroxide aqueous solution were continuously added, The resulting reaction mixture was continuously removed. The reaction product thus obtained was washed with pure water and then dried overnight at 105 ° C. to obtain nickel hydroxide powder. A scanning electron micrograph of the nickel hydroxide particles is shown in FIG.
[0045]
The obtained nickel hydroxide particles have a spherical shape with a secondary particle diameter of 10 μm in which primary particles with a primary particle diameter of 0.1 μm or less aggregated, and N 2 -Specific surface area by BET method is 34.1m 2 / G.
[0046]
Example 6
Pure water was added to 38.9 g of the spherical nickel hydroxide particles obtained in Comparative Example 1 and 111 g of ammonium sulfate to a volume of 150 mL, which was sufficiently stirred. To this was added 263 g of 22% aqueous ammonia and 171 g of 19.6% caustic soda solution, and this was charged into a 1 L autoclave and heat-treated at 250 ° C. for 20 hours. After completion of the reaction, the reaction mixture was cooled and treated in the same manner as in Example 1 to obtain 5.5 g of nickel hydroxide powder. A scanning electron micrograph of the nickel hydroxide particles is shown in FIG.
[0047]
The obtained nickel hydroxide particles have a plate shape with a primary particle diameter of 1.8 μm and an average thickness of 0.72 μm, and N 2 -Specific surface area by BET method is 1.6m 2 / G.
[0048]
Example 7
While stirring with a disper, 273 g of 19.6% aqueous sodium hydroxide solution was added to 324 g of 23.6% aqueous nickel nitrate solution to neutralize it, and then added with 13.2 g of 22% aqueous ammonia and 80.7 g of ammonium nitrate, Pure water was added to bring the total volume to 600 mL, followed by stirring for 30 minutes. This was transferred into a 1 L autoclave and heat-treated at 250 ° C. for 96 hours. After completion of the reaction, the resulting reaction mixture was treated in the same manner as in Example 1 to obtain nickel hydroxide powder.
[0049]
The obtained nickel hydroxide particles have a plate shape with a primary particle diameter of 1.0 μm and an average thickness of 0.14 μm. 2 -Specific surface area by BET method is 4.4m 2 / G.
[0050]
Comparative Example 2
The reaction was conducted in the same manner as in Example 4 except that the reaction temperature was 90 ° C. The obtained nickel hydroxide is a fine particle having a primary particle size of 0.2 μm or less as shown in a scanning electron micrograph of FIG. 2 -Specific surface area by BET method is 20.1m 2 / G.
[0051]
Comparative Example 3
The reaction was carried out in the same manner as in Example 7 except that the reaction temperature in the autoclave was 90 ° C., and nickel hydroxide was obtained as secondary agglomerated particles composed of fine primary particles having a primary particle size of 0.1 μm. N of the nickel hydroxide particles 2 -Specific surface area by BET method is 21.5m 2 / G.
[0052]
[Table 1]
(Manufacture of lithium nickel composite oxide)
Example 8
30 g of the nickel hydroxide powder obtained in Example 2 and 13.6 g of lithium hydroxide monohydrate pulverized in an automatic mortar were placed in a polyethylene bag and thoroughly mixed. 10 g of the mixture thus obtained was put in an alumina crucible, heated at a rate of 200 ° C./hour in an oxygen atmosphere, and then baked at 800 ° C. for 10 hours. Thereafter, it was cooled to room temperature at a rate of 200 ° C./hour to obtain lithium nickel composite oxide particles.
[0054]
A scanning electron micrograph of the lithium nickel composite oxide particles is shown in FIG. 9, and FIG. 10 shows an X-ray diffraction pattern measured using Cu-Kα rays. From this, it was confirmed that the obtained lithium nickel composite oxide was a lithium nickelate single phase. It was confirmed by this X-ray diffraction pattern that the obtained particles were lithium nickelate. The obtained lithium nickel composite oxide particles have a primary particle average major axis diameter of 5 μm and an average thickness of 0.5 μm, and have a large particle size plate particle that strongly inherits the shape of the nickel hydroxide particles used as a raw material. Met.
[0055]
Comparative Example 4
A reaction was performed in the same manner as in Example 8 except that the nickel hydroxide powder obtained in Comparative Example 1 was used to obtain lithium nickel composite oxide particles. As shown in FIG. 11, a scanning electron micrograph of this particle is a spherical particle having a fine structure on the surface, strongly inheriting the shape of nickel hydroxide used as a raw material, although some growth of primary particles is observed. there were.
[Brief description of the drawings]
1 is a scanning electron micrograph (magnification 1000 times) of the nickel hydroxide particles obtained in Example 1. FIG.
FIG. 2 is a photograph taken by tilting the sample stage when taking a scanning electron micrograph of the nickel hydroxide particles obtained in Example 1 (1000 ×).
FIG. 3 is a scanning electron micrograph (5000 magnifications) of the nickel hydroxide particles obtained in Example 2.
4 is an X-ray diffraction pattern of nickel hydroxide particles obtained in Example 2. FIG. The vertical axis represents the X-ray intensity (CPS), and the horizontal axis represents the diffraction angle (2θ).
5 is a scanning electron micrograph (10,000 magnifications) of the nickel hydroxide particles obtained in Example 4. FIG.
6 is a scanning electron micrograph (5000 magnifications) of the nickel hydroxide particles obtained in Comparative Example 1. FIG.
7 is a scanning electron micrograph (magnification 5000 times) of the nickel hydroxide particles obtained in Example 6. FIG.
8 is a scanning electron micrograph (10,000 magnifications) of the nickel hydroxide particles obtained in Comparative Example 2. FIG.
FIG. 9 is a scanning electron micrograph (magnification 5000 times) of the lithium-nickel composite oxide particles obtained in Example 8.
10 is an X-ray diffraction pattern of lithium-Nickel composite oxide particles obtained in Example 8. FIG.
FIG. 11 shows Comparative Example 4 2 is a scanning electron micrograph (x5000) of the lithium-nickel composite oxide particles obtained in 1).
Claims (7)
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| JP19035797A JP4066472B2 (en) | 1997-06-10 | 1997-06-10 | Plate-like nickel hydroxide particles, method for producing the same, and method for producing lithium / nickel composite oxide particles using the same as a raw material |
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| JP19035797A JP4066472B2 (en) | 1997-06-10 | 1997-06-10 | Plate-like nickel hydroxide particles, method for producing the same, and method for producing lithium / nickel composite oxide particles using the same as a raw material |
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| JP2005194156A (en) * | 2004-01-09 | 2005-07-21 | Ishikawajima Harima Heavy Ind Co Ltd | Method of manufacturing nickel hydroxide powder |
| KR101088255B1 (en) | 2006-12-22 | 2011-11-30 | 파나소닉 주식회사 | Nickel hydroxide, method for producing positive electrode active material for non-aqueous electrolyte secondary battery, electrode for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery |
| JP2009173495A (en) * | 2008-01-25 | 2009-08-06 | Univ Of Miyazaki | Nickel hydroxide nanosheet and its manufacturing method |
| JP5087789B2 (en) * | 2008-03-13 | 2012-12-05 | 住友金属鉱山株式会社 | Method for producing plate-like lithium nickel composite oxide and plate-like lithium nickel composite oxide using the same |
| JP2010037163A (en) * | 2008-08-06 | 2010-02-18 | Univ Of Miyazaki | Nickel hydroxide hexagonal plate and its manufacturing method |
| JP5568849B2 (en) * | 2008-09-09 | 2014-08-13 | 住友金属鉱山株式会社 | Plate-like nickel-containing hydroxide, method for producing the same, plate-like nickel-containing oxyhydroxide using the same, and method for producing the same |
| JP5590283B2 (en) * | 2008-09-22 | 2014-09-17 | 住友金属鉱山株式会社 | Lithium composite nickel oxide and method for producing the same |
| CN102134108B (en) * | 2011-03-18 | 2012-10-17 | 宇辰新能源材料科技无锡有限公司 | Preparation method of wrinkled-paper-like nano nickel hydroxide and nickel oxide with high specific surface areas |
| CN103022466A (en) * | 2011-09-20 | 2013-04-03 | 中国科学院福建物质结构研究所 | High capacity solid solution composite positive electrode material preparation method |
| JP5527630B2 (en) * | 2012-04-23 | 2014-06-18 | 国立大学法人 宮崎大学 | Nickel hydroxide nanosheet and method for producing the same |
| WO2013183711A1 (en) * | 2012-06-06 | 2013-12-12 | 住友金属鉱山株式会社 | Nickel composite hydroxide, positive electrode active material for non-aqueous electrolyte secondary cell, non-aqueous electrolyte secondary cell, and methods for producing these |
| JP5618387B2 (en) * | 2012-12-27 | 2014-11-05 | 国立大学法人宮崎大学 | Nickel hydroxide hexagonal plate and manufacturing method thereof |
| JP5880426B2 (en) * | 2012-12-28 | 2016-03-09 | 住友金属鉱山株式会社 | Nickel composite hydroxide, method for producing the same, and method for producing positive electrode active material |
| JP6456630B2 (en) | 2013-09-18 | 2019-01-23 | 株式会社東芝 | Non-aqueous electrolyte battery |
| JP5874939B2 (en) * | 2014-05-30 | 2016-03-02 | 住友金属鉱山株式会社 | Nickel-containing hydroxide, nickel-containing oxide, and production method thereof |
| JP6252384B2 (en) | 2014-06-27 | 2017-12-27 | 住友金属鉱山株式会社 | Nickel composite hydroxide and manufacturing method thereof, positive electrode active material and manufacturing method thereof, and non-aqueous electrolyte secondary battery |
| JP6252383B2 (en) | 2014-06-27 | 2017-12-27 | 住友金属鉱山株式会社 | Manganese cobalt composite hydroxide and method for producing the same, positive electrode active material and method for producing the same, and non-aqueous electrolyte secondary battery |
| KR101745335B1 (en) * | 2016-10-21 | 2017-06-13 | 한국에너지기술연구원 | Electrode for Electrolysis and the Fabrication Method Thereof |
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