【０００１】
【発明の属する技術分野】
本発明は、リチウムイオン電池正極材料用原料水酸化物、及び該リチウムイオン電池正極材料用原料水酸化物を原料に用いたリチウムイオン電池正極材料に関する。
【０００２】
【従来技術】
近年、組成式Ｌｉ（Ｎｉｘ，Ｃｏｙ，Ｍｎｚ）Ｏ２（ｘ＋ｙ＋ｚ＝１）で表されるリチウムイオン電池正極材料を、Ｌｉイオン二次電池の正極材に用いた電池が、多く市販されるに到っている。
【０００３】
しかし、組成式Ｌｉ（Ｎｉｘ，Ｃｏｙ，Ｍｎｚ）Ｏ２（ｘ＋ｙ＋ｚ＝１）で表されるリチウムイオン電池正極材料は、電池内により多くの材料を詰め込めるようにするために高タップ密度化が要求される。組成式Ｌｉ（Ｎｉｘ，Ｃｏｙ，Ｍｎｚ）Ｏ２（ｘ＋ｙ＋ｚ＝１）で表されるリチウムイオン電池正極材料の合成方法の一つに、水溶液反応によりＮｉ，Ｃｏ，Ｍｎの共沈原料（水酸化物あるいは炭酸塩等）を作成し、これにリチウム化合物を混合して焼成する方法がある。このため、タップ密度が大きいＬｉ（Ｎｉｘ，Ｃｏｙ，Ｍｎｚ）Ｏ２（ｘ＋ｙ＋ｚ＝１）を得るためには、タップ密度が大きいＮｉ，Ｃｏ，Ｍｎの共沈原料（水酸化物あるいは炭酸塩等）を合成する事が必要となる。
【０００４】
タップ密度が大きい水酸化ニッケル（Ｎｉの一部がＣｏ，Ａｌ，Ｍｎで置換されたものを含む）の作成方法は特許文献１等に開示されている。しかし、反応ｐＨが広域（１１．０〜１３．０）に渡っており、また反応槽内での粉末の滞留時間が、反応槽の容積（５００ｌ）と硫酸ニッケル等の添加速度から算出すると２７時間以上となり、生産性の向上が求められている。また、ニッケルイオンを一度アンモニアと錯体を形成させてから反応槽内のアルカリ中へ連続的に添加することで水酸化物を得る方法も知られている。ニッケルイオンをアルカリ中に直接添加すると、ニッケルイオンと水酸化物イオンの反応が速いために核発生が多くなり、結晶が微細化し、結果として隙間の多い凝集粒ができてしまいタップ密度の低い水酸化物粒子になってしまう。そこで、ニッケルイオンを一度アンモニアと錯形成させてからアルカリ中に添加すると、ニッケルはアンモニアに配位しているために、水酸化物イオンと接触した場合の反応が遅くなり、核発生が抑制される。これにより、滴下したニッケルイオンは新たな核を生成する事が抑制されて、既に存在している粒子上に析出し易くなり、且つ粒子の方位も揃ってくるために密な二次粒子が形成されて、タップ密度が大きな水酸化ニッケル粒子が生成する。
【０００５】
しかし、この方法で（Ｎｉｘ，Ｃｏｙ，Ｍｎｚ）（ＯＨ）２（ｘ＋ｙ＋ｚ＝１）を得ようとすると、ＣｏあるいはＭｎがアンモニアと接触した時点で水酸化物として析出して微細な粒子となるばかりでなく、最終的に得られる物質は不定形でタップ密度が小さなものになってしまう。これを原料にＬｉ（Ｎｉｘ，Ｃｏｙ，Ｍｎｚ）Ｏ２（ｘ＋ｙ＋ｚ＝１）を焼成しても、高タップ密度なものは得られない。
【０００６】
【特許文献１】
特開２００２−２０１０２８号公報
【０００７】
【発明が解決しようとする課題】
本発明は、このような事情に鑑み、タップ密度が高い原料、及びこれを原料に用いた正極材料もタップ密度が高くできる電池特性の優れたリチウムイオン二次電池用正極材料を提供することを課題とする。
【０００８】
【課題を解決するための手段】
我々は、鋭意研究の結果、Ｎｉ，Ｃｏ，Ｍｎの混合水溶液（場合によりＡｌ，Ｍｇ，Ｔｉを含む）とアンモニア水溶液を別々に連続的に反応槽内に供給し、且つｐＨを低く調整して反応溶液中にアンミン錯イオンを残したまま、連続的に合成し、且つ連続的に回収するとタップ密度が高い水酸化物粒子が得られることを見出した。すなわち、反応溶液中のｐＨを下げることで、金属塩の原料液が液中に添加されたときに核発生反応速度が抑制され、添加された金属イオンは既に存在している粒子上に析出し易くなる。また、アンミン錯イオンが溶液中に存在していることで、水酸化物粒子の溶解・析出反応が加速され、微小な粒子は溶解し、大きな粒子状に再析出しやすくなる。これにより、微粉が少ない、且つよく詰まったタップ密度が大きい水酸化物粒子が生成できると推察される。これを原料に焼成した組成式Ｌｉ１＋ａ（Ｎｉ１−ｘ−ｙ−ｚ，Ｃｏｘ，Ｍｎｙ，Ｍｚ）１−ａＯ２（場合によりＭ＝ Ａｌ，Ｍｇ，Ｔｉを含む）で表されるリチウムイオン電池正極材料はタップ密度が大きくなるばかりでなく比表面積が小さい割りには電池容量が高い材料が得られる。
【０００９】
しかし、反応では母液中に常にニッケルのアンミン錯イオンが溶解した状態になっているため、得られた水酸化物粒子を回収するときに廃液中にニッケルアンミン錯イオンが溶解しており、これを回収する事が必要になってくる。
【００１０】
廃液中にニッケルを残さないようにする方法として、反応槽を二段にして合成する方法がある。一段目の反応槽で生成した水酸化物とニッケルアンミン錯イオンを含む溶液が二段目の反応槽に入り、ここに水酸化ナトリウムを供給してｐＨをあげることで、溶液中のニッケルが水酸化物として析出する。このとき、別の粒子として析出するものも若干あると考えられるが、その殆どが一段目で生成した水酸化物粒子の上に析出すると考えられる。このため、ニッケルを後から沈降させたにもかかわらず微粉の少ない、タップ密度の高い原料水酸化物粒子が得られる。
【００１１】
これを原料に焼成した組成式Ｌｉ１＋ａ（Ｎｉ１−ｘ−ｙ−ｚ，Ｃｏｘ，Ｍｎｙ，Ｍｚ）１−ａＯ２（場合によりＭ＝ Ａｌ，Ｍｇ，Ｔｉを含む）で表されるリチウムイオン電池正極材料も同様にタップ密度が大きいだけでなく、比表面積が小さい割には電池容量が高い材料が得られる。
【００１２】
そこで、本発明の第１の態様は、組成式 （Ｎｉ１−ｘ−ｙ−ｚ，Ｃｏｘ，Ｍｎｙ，Ｍｚ）（ＯＨ）２（場合によりＭ＝Ａｌ，Ｍｇ，Ｔｉを含む）で表されるリチウムイオン電池正極材料用原料水酸化物であって、タップ密度が１．０ｇ／ｃｍ３以上であることを特徴とする、組成式Ｌｉ１＋ａ（Ｎｉ１−ｘ−ｙ−ｚ，Ｃｏｘ，Ｍｎｙ，Ｍｚ）１−ａＯ２（場合によりＭ＝ Ａｌ，Ｍｇ，Ｔｉを含む）で表されるリチウムイオン電池正極材料の原料に用いるリチウムイオン電池正極材料用原料水酸化物である。
【００１３】
本発明の第２の態様は、溶液中にニッケルアンミン錯イオンが存在する状態で、アンモニアとＮｉ， Ｃｏ， Ｍｎ，Ｍ塩溶液（場合によりＭ＝Ａｌ，Ｍｇ，Ｔｉ塩溶液を含む）を別々に、且つ連続的に供給して水酸化物として合成することを特徴とする請求項１記載のリチウムイオン電池正極材料用原料水酸化物にある。ここで、溶液中にニッケルアンミン錯イオンが存在する状態とは、例えば、硫酸ニッケル、アンモニア水の存在下でｐＨ１１．４〜１１．７にすると実現できる。
【００１４】
本発明の第３の態様は、請求項２で得られた水酸化物とアンミン錯イオンが共存する溶液にアルカリを添加してｐＨをあげて、溶液中のニッケルイオンを溶液中に存在する水酸化物粒子の上に沈降させて得られる請求項１記載のリチウムイオン電池正極材料用原料水酸化物にある。
【００１５】
本発明の第４の態様は、請求項１記載のリチウムイオン電池正極材料用原料水酸化物にリチウム化合物を混合して、焼成して得られた組成式Ｌｉ１＋ａ（Ｎｉ１−ｘ−ｙ−ｚ，Ｃｏｘ，Ｍｎｙ，Ｍｚ）１−ａＯ２（場合によりＭ＝ Ａｌ，Ｍｇ，Ｔｉを含む）で表されるリチウムイオン電池正極材料にある。
【００１６】
本発明の第５の態様は、請求項１記載のリチウムイオン電池正極材料用原料水酸化物にリチウム化合物とフッ素化合物を混合して、焼成して得られる組成式Ｌｉ１＋ａ（Ｎｉ１−ｘ−ｙ−ｚ，Ｃｏｘ，Ｍｎｙ，Ｍｚ）１−ａＯ２−ｖＦｖ（場合によりＭ＝ Ａｌ，Ｍｇ，Ｔｉを含む）で表されるリチウムイオン電池正極材料にある。
【００１７】
【発明の実施の形態】
次に、本発明を実施例及び比較例に基づいてさらに詳細に説明する。
【００１８】
（実施例１）
硫酸ニッケル１５．２４９ｋｇ、硫酸コバルト１４．０５５ｋｇ、硫酸マンガン１１．７５６ｋｇを８０ｌの水に溶解させ、また、水酸化ナトリウム６ｍｏｌ／ｌ、アンモニア水を原料液として用いた。反応槽の概略図を図１に示す。反応槽は２．２ｌのものを用い、合成中は反応液中にアルゴンガスを０．５ｌ／ｍｉｎでバブリングし、反応液が空気と接触しないように密閉構造とした。また、反応槽は二重ジャケットにより４０℃に保温した。なお、二重ジャケットと恒温槽（図示しない）間で温水を循環させた。反応液は、攪拌モーターを用いて１０００ｒｐｍで攪拌し、反応槽内は図に示すような対流が起こるようにした。Ｎｉ，Ｃｏ，Ｍｎ溶液を８．０ｍｌ／ｍｉｎ、水酸化ナトリウム水溶液を４．９ｍｌ／ｍｉｎ、アンモニア水を１．２ｍｌ／ｍｉｎで反応槽内に供給して合成した。このとき、反応槽内のｐＨは１１．４〜１１．７になるようにした。得られた共沈粉は、デカンテーション水洗を行い、ろ過、乾燥して原料粉とした。
【００１９】
得られた原料粉１２５ｇと炭酸リチウム５８．６２ｇを混合し、電気炉を用いて９００℃で２０時間焼成してＬｉイオン電池正極材料を得た。このとき、昇降温速度は３０℃／ｈｒで設定した。電池特性は、得られた正極材：ＴＡＢ２＝２：１で混合したものを隙間を５０μｍに調整したローラーを用いてシート状に圧延し、１３φｍｍのポンチで打ち抜いて正極に用いた。対極にはＬｉメタルを、電解液には１Ｍ−ＬｉＰＦ６／（ＥＣ：ＤＭＣ＝１：１）を用いた。ここで、ＴＡＢ２とは非水溶液系の電池に用いられる導電剤とバインダーの複合剤で、テフロナイズドアセチレンブラック（テトラフルオロエチレンバインダーとアセチレンブラックの複合剤）の略称である。電池の充放電は４．３Ｖ−３．０Ｖの範囲で行なった。得られた原料粉の物性、化学分析値、及び反応槽から出てきた液中のＮｉ，Ｃｏ，Ｍｎの濃度を表１，２に示す。また、焼成粉の物性、電池特性、及び化学分析値を表３，４に示す。なお、反応槽から出てきた液中のＣｏ，Ｍｎの濃度はいずれも０．０１ｇ／ｍｌ以下であったが、コバルト、マンガンのアンミン錯イオンの安定度はニッケルイオンよりも低いため、アンモニアの存在下ではニッケルが優先してアンミン錯イオンとして水溶液中に存在する。反応液がアルカリであるため、コバルト、マンガンはほとんど水酸化物粒子として沈降していると考えられる。そのため、反応液中にコバルト、マンガンが殆ど溶解していないと考えられる。
【００２０】
以上より、実施例１において、ｐＨ域を狭い範囲（１１．４〜１１．７）にコントロールすることにより、生産性良く高タップ密度のリチウムイオン電池正極材料用原料水酸化物を得ることができる。即ち、反応槽内での粉末の滞留時間が、反応槽の容積（２．２ｌ）と硫酸ニッケル等の添加速度から算出すると約３時間程度である。
【００２１】
【表１】
【００２２】
【表２】
【００２３】
【表３】
【００２４】
【表４】
【００２５】
実施例２
硫酸ニッケル１４．１０２ｋｇ、硫酸コバルト１５．１１１ｋｇ、硫酸マンガン１２．９０８ｋｇを８０ｌの水に溶解させ、また、水酸化ナトリウム６ｍｏｌ／ｌ、アンモニア水を原料液として用いた。反応槽の概略図を図２に示す。一段目には２．２ｌの反応槽を、二段目には１ｌの反応槽を用いた。実施例１の場合と同じように、一段目、二段目共に反応槽は二重ジャケットにより４０℃に保温し、アルゴンガスをバブリングし、密閉構造とした。反応液は、攪拌モーターを用いて一段目が１０００ｒｐｍ、二段目は１６００ｒｐｍで攪拌し、反応槽内は図に示すような対流が起こるようにした。一段目の反応槽へはＮｉ，Ｃｏ，Ｍｎ溶液を８ｍｌ／ｍｉｎ、水酸化ナトリウム水溶液を４．９ ｍｌ／ｍｉｎ、アンモニア水を１．２ｍｌ／ｍｉｎで反応槽内に供給して合成し、このとき、反応槽内のｐＨは１１．４〜１１．７になるようにした。反応液は二段目の反応槽内へ供給される。二段目の反応槽へは水酸化ナトリウム水溶液を０．５ｍｌ／ｍｉｎで供給し、反応槽内の液のｐＨは１２．３〜１２．８になるようにした。得られた共沈粉は、デカンテーション水洗を行い、ろ過、乾燥して原料粉とした。
【００２６】
得られた原料粉１２５ｇと炭酸リチウム５８．９８ｇを混合し、電気炉を用いて９００℃で２０時間焼成してＬｉイオン電池正極材料を得た。このとき、昇降温速度は３０℃／ｈｒで設定した。得られた原料粉・焼成粉は、実施例１の場合と同様な方法で評価を行った。得られた原料粉の物性、化学分析値、及び反応槽から出てきた液中のＮｉ，Ｃｏ，Ｍｎの濃度を表１，２に示す。また、焼成粉の物性、電池特性、及び化学分析値を表３，４に示す。
【００２７】
［実施例３］
硫酸ニッケル１５．０９７ｋｇ、硫酸コバルト１３．９１４ｋｇ、硫酸マンガン１１．６３８ｋｇ、硫酸マグネシウム３９８．４ｇを８０ｌの水に溶解させ、また、水酸化ナトリウム６ｍｏｌ／ｌ、アンモニア水を原料液として用い、実施例１の場合と同様に原料粉を調整した。
得られた原料粉１２５ｇと炭酸リチウム５７．６３ｇを混合し、電気炉を用いて９００℃で２０時間焼成してＬｉイオン電池正極材料を得た。このとき、昇降温速度は３０℃／ｈｒで設定した。得られた原料粉・焼成粉は、実施例１の場合と同様な方法で評価を行った。得られた原料粉の物性、化学分析値、及び反応槽から出てきた液中のＮｉ，Ｃｏ，Ｍｎの濃度を表１，２に示す。また、焼成粉の物性、電池特性、及び化学分析値を表３，４に示す。
【００２８】
［実施例４］
硫酸ニッケル１５．０９７ｋｇ、硫酸コバルト１３．９１４ｋｇ、硫酸マンガン１１．６３８ｋｇ、Ａｌの濃度を１．７５Ｍに調整した硫酸アルミニウム水溶液０．９１３ｌを８０ｌの水に溶解させ、また、水酸化ナトリウム６ｍｏｌ／ｌ、アンモニア水を原料液として用い、実施例１の場合と同様に原料粉を調整した。得られた原料粉１２５ｇと炭酸リチウム５７．３１ｇを混合し、電気炉を用いて９００℃で２０時間焼成してＬｉイオン電池正極材料を得た。このとき、昇降温速度は３０℃／ｈｒで設定した。得られた原料粉・焼成粉は、実施例１の場合と同様な方法で評価を行った。得られた原料粉の物性、化学分析値、及び反応槽から出てきた液中のＮｉ，Ｃｏ，Ｍｎの濃度を表１，２に示す。また、焼成粉の物性、電池特性、及び化学分析値を表３，４に示す。
【００２９】
［実施例５］
硫酸ニッケル１５．０９７ｋｇ、硫酸コバルト１３．９１４ ｋｇ、硫酸マンガン１１．６３８ｋｇ、硫酸チタン７８０ｇを８０ｌの水に溶解させ、また、水酸化ナトリウム６ｍｏｌ／ｌ、アンモニア水を原料液として用い、実施例１の場合と同様に原料粉を調整した。
得られた原料粉１２５ｇと炭酸リチウム５８．２２ｇを混合し、電気炉を用いて９００℃で２０時間焼成してＬｉイオン電池正極材料を得た。このとき、昇降温速度は３０℃／ｈｒで設定した。得られた原料粉・焼成粉は、実施例１の場合と同様な方法で評価を行った。得られた原料粉の物性、化学分析値、及び反応槽から出てきた液中のＮｉ，Ｃｏ，Ｍｎの濃度を表１，２に示す。また、焼成粉の物性、電池特性、及び化学分析値を表３，４に示す。
【００３０】
［実施例６］
実施例１で得られた原料粉１２５ｇと炭酸リチウム５６．９２ｇを混合し、電気炉を用いて９００℃で２０時間焼成し、得られた粉末にＬｉＦ０．７１ｇを添加して７００℃で１０ｈｒ焼成してＬｉイオン電池正極材料を得た。このとき、昇降温速度は一段目の焼成は３０℃／ｈｒで設定し、二段目の焼成は１４０℃／ｈｒで設定した。得られた原料粉・焼成粉は、実施例１の場合と同様な方法で評価を行った。得られた原料粉の物性、化学分析値、及び反応槽から出てきた液中のＮｉ，Ｃｏ，Ｍｎの濃度を表１，２に示す。また、焼成粉の物性、電池特性、及び化学分析値を表３，４に示す。
【００３１】
［比較例１］
硫酸ニッケル１４．１０２ｋｇ、硫酸コバルト１５．１１１ｋｇ、硫酸マンガン１２．９０８ｋｇを８０ｌの水に溶解させ、また、水酸化ナトリウム６ｍｏｌ／ｌ、アンモニア水を原料液として用いた。反応槽は実施例１で使用したものと同じものを用い、液温、攪拌速度、対流、窒素バブリングは同じ条件で行なった。Ｎｉ，Ｃｏ，Ｍｎ溶液を８ｍｌ／ｍｉｎ、水酸化ナトリウム水溶液を５．５ｍｌ／ｍｉｎ、アンモニア水を１．２ ｍｌ／ｍｉｎで反応槽内に供給して合成した。このとき、反応槽内のｐＨは１２．３〜１２．８になるようにした。得られた共沈粉は、デカンテーション水洗を行い、ろ過、乾燥して原料粉とした。
【００３２】
得られた原料粉１２５ｇと炭酸リチウム５８．０８ｇを混合し、電気炉を用いて１０００℃で２０時間焼成してＬｉイオン電池正極材料を得た。このとき、昇降温速度は３０℃／ｈｒで設定した。得られた原料粉・焼成粉は、実施例１の場合と同様な方法で評価を行った。得られた原料粉の物性、化学分析値、及び反応槽から出てきた液中のＮｉ，Ｃｏ，Ｍｎの濃度を表１，２に示す。また、焼成粉の物性、電池特性、及び化学分析値を表３，４に示す。本法で合成した原料は、タップ密度が高く、これを原料に用いた正極材料もタップ密度が高くできる。結果を表１に示す。表３によると、実施例と比較例とで単位重量当たりの放電容量の差は見られなかったが、単位体積当たりとすると、高タップ密度品の放電容量は優れていることがわかる。
【００３３】
【発明の効果】
以上説明したように、本発明によるとタップ密度が高いリチウムイオン電池正極材料用原料水酸化物が得られ、該リチウムイオン電池正極材料用原料水酸化物を原料に用いたリチウムイオン電池正極材は高タップ密度であり、これをリチウムイオン電池に用いると、電極に活物質の充填量を増大させる事が出来、結果的に単位体積あたりの容量を増大させるという効果を奏する。
【図面の簡単な説明】
【図１】本発明に関する反応槽の概略図。
【図２】本発明に関する反応槽の概略図。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a raw material hydroxide for a lithium ion battery positive electrode material, and a lithium ion battery positive electrode material using the raw material hydroxide for a lithium ion battery positive electrode material as a raw material.
[0002]
[Prior art]
In recent years, many batteries using the lithium ion battery cathode material represented by the composition formula Li (Ni x , Co y , Mn z ) O 2 (x + y + z = 1) as the cathode material of a Li ion secondary battery are commercially available. Has been reached.
[0003]
However, the lithium ion battery cathode material represented by the composition formula Li (Ni x , Co y , Mn z ) O 2 (x + y + z = 1) has a high tap density in order to pack more materials in the battery. Required. One of the methods for synthesizing a lithium ion battery cathode material represented by the composition formula Li (Ni x , Co y , Mn z ) O 2 (x + y + z = 1) is a coprecipitation raw material (water, Ni, Co, Mn) by an aqueous solution reaction. There is a method in which an oxide or a carbonate is prepared, a lithium compound is mixed therein, and the mixture is baked. Therefore, in order to obtain Li (Ni x , Co y , Mn z ) O 2 (x + y + z = 1) having a large tap density, a coprecipitating material (hydroxide or carbonate) of Ni, Co, Mn having a large tap density is required. Etc.) must be synthesized.
[0004]
Patent Document 1 and the like disclose a method for producing nickel hydroxide having a large tap density (including one in which a part of Ni is replaced with Co, Al, and Mn). However, the reaction pH ranges over a wide range (11.0 to 13.0), and the residence time of the powder in the reaction tank is calculated from the volume of the reaction tank (500 l) and the addition rate of nickel sulfate or the like. It is more than time, and improvement of productivity is required. There is also known a method in which nickel ions are once formed into a complex with ammonia and then continuously added to an alkali in a reaction tank to obtain a hydroxide. When nickel ions are directly added to an alkali, the reaction between nickel ions and hydroxide ions is fast, so nucleation is increased, crystals are refined, and consequently, aggregated particles with many gaps are formed and water having a low tap density is obtained. It becomes oxide particles. Therefore, if nickel ions are once complexed with ammonia and then added to an alkali, nickel is coordinated with ammonia, so the reaction when contacted with hydroxide ions is slowed, and nucleation is suppressed. You. As a result, the dropped nickel ions are prevented from generating new nuclei, are easily deposited on the existing particles, and form dense secondary particles because the orientation of the particles is uniform. As a result, nickel hydroxide particles having a large tap density are generated.
[0005]
However, in this method (Ni x, Co y, Mn z) (OH) 2 (x + y + z = 1) and is to be obtained, fine particles precipitated as a hydroxide at the time the Co or Mn is in contact with ammonia In addition to this, the substance finally obtained is indefinite and has a low tap density. Li this raw material (Ni x, Co y, Mn z) be fired O2 (x + y + z = 1), can not be obtained as high tap density.
[0006]
[Patent Document 1]
JP-A-2002-201028
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and provides a raw material having a high tap density, and a positive electrode material for a lithium ion secondary battery having excellent battery characteristics that enables a positive electrode material using the raw material to have a high tap density. Make it an issue.
[0008]
[Means for Solving the Problems]
As a result of our intensive research, we have continuously and separately supplied a mixed aqueous solution of Ni, Co, and Mn (including Al, Mg, and Ti in some cases) and an aqueous ammonia solution, and adjusted the pH to be low. It has been found that hydroxide particles having a high tap density can be obtained by continuously synthesizing and continuously collecting the ammine complex ion while leaving the ammine complex ion in the reaction solution. That is, by lowering the pH in the reaction solution, the nucleation reaction rate is suppressed when the metal salt raw material solution is added to the solution, and the added metal ions precipitate on the already existing particles. It will be easier. In addition, the presence of the ammine complex ion in the solution accelerates the dissolution / precipitation reaction of the hydroxide particles, so that the fine particles are dissolved and easily reprecipitated into large particles. Thereby, it is presumed that hydroxide particles having a small amount of fine powder and well packed and having a large tap density can be generated. Formula which was calcined material Li1 + a (Ni1-x- y-z, Cox, Mny, Mz) lithium-ion battery cathode material represented by 1-aO 2 (optionally including M = Al, Mg, and Ti by) In addition to the increase in tap density, a material having a high battery capacity can be obtained for a small specific surface area.
[0009]
However, in the reaction, the nickel ammine complex ion is always dissolved in the mother liquor, so when recovering the obtained hydroxide particles, the nickel ammine complex ion is dissolved in the waste liquid. It becomes necessary to collect it.
[0010]
As a method for preventing nickel from remaining in the waste liquid, there is a method of synthesizing the reaction tank in two stages. The solution containing hydroxide and nickel ammine complex ions generated in the first reaction tank enters the second reaction tank, and sodium hydroxide is supplied thereto to raise the pH, whereby nickel in the solution is converted into water. Precipitates as oxide. At this time, it is considered that some of the particles precipitate as separate particles, but most of them are considered to precipitate on the hydroxide particles generated in the first step. For this reason, the raw material hydroxide particles having a small tapping density and a high tap density can be obtained despite the precipitation of nickel later.
[0011]
Formula which was calcined material Li1 + a (Ni1-x- y-z, Cox, Mny, Mz) lithium-ion battery cathode material represented by 1-aO 2 (optionally including M = Al, Mg, and Ti by) Similarly, not only the tap density is high, but also a material having a high battery capacity is obtained for a small specific surface area.
[0012]
Accordingly, a first aspect of the present invention provides a lithium battery represented by a composition formula (Ni1-xyz, Cox, Mny, Mz) (OH) 2 (including M = Al, Mg, and Ti in some cases). A compositional formula Li1 + a (Ni1-xyz, Cox, Mny, Mz) 1 which is a raw material hydroxide for an ion battery positive electrode material and has a tap density of 1.0 g / cm 3 or more. -aO is 2 (optionally M = Al, Mg, including Ti) material hydroxide for lithium-ion battery cathode materials for use in the raw material of the lithium-ion battery cathode material represented by.
[0013]
According to a second aspect of the present invention, ammonia and Ni, Co, Mn, M salt solutions (including M = Al, Mg, Ti salt solutions in some cases) are separated in the presence of nickel ammine complex ions in the solution. 2. The raw material hydroxide for a lithium ion battery positive electrode material according to claim 1, wherein the raw material hydroxide is supplied continuously and synthesized as a hydroxide. Here, the state in which the nickel ammine complex ion is present in the solution can be realized, for example, by adjusting the pH to 11.4 to 11.7 in the presence of nickel sulfate and aqueous ammonia.
[0014]
According to a third aspect of the present invention, the pH is increased by adding an alkali to the solution in which the hydroxide and the ammine complex ion coexist, and the nickel ions in the solution are added to the water present in the solution. 2. The raw material hydroxide for a lithium ion battery cathode material according to claim 1, which is obtained by sedimentation on oxide particles.
[0015]
According to a fourth aspect of the present invention, there is provided a composition formula Li1 + a (Ni1-xyz, obtained by mixing a lithium compound with the raw material hydroxide for a lithium ion battery positive electrode material according to claim 1 and firing the mixture. Cox, Mny, Mz) is 1-aO 2 (optionally M = Al, Mg, lithium-ion battery cathode materials expressed by containing Ti).
[0016]
In a fifth aspect of the present invention, a composition formula Li1 + a (Ni1-xy-) obtained by mixing a lithium compound and a fluorine compound with the raw material hydroxide for a lithium ion battery cathode material according to claim 1 and firing the mixture. z, Cox, Mny, Mz) 1-aO2-vFv (M = including Al, Mg, and Ti in some cases).
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the present invention will be described in more detail based on examples and comparative examples.
[0018]
(Example 1)
15.249 kg of nickel sulfate, 14.55 kg of cobalt sulfate, and 11.756 kg of manganese sulfate were dissolved in 80 l of water, and 6 mol / l of sodium hydroxide and ammonia water were used as a raw material liquid. FIG. 1 shows a schematic view of the reaction tank. The reaction tank used was 2.2 l, and argon gas was bubbled into the reaction liquid at 0.5 l / min during the synthesis to form a closed structure so that the reaction liquid did not come into contact with air. The temperature of the reactor was kept at 40 ° C. by a double jacket. Note that hot water was circulated between the double jacket and a thermostat (not shown). The reaction solution was stirred at 1000 rpm using a stirring motor so that convection as shown in the figure occurred in the reaction tank. Ni, Co, and Mn solutions were supplied into the reactor at 8.0 ml / min, an aqueous solution of sodium hydroxide at 4.9 ml / min, and aqueous ammonia at 1.2 ml / min. At this time, the pH in the reaction tank was adjusted to 11.4 to 11.7. The obtained coprecipitated powder was washed with decantation water, filtered and dried to obtain a raw material powder.
[0019]
125 g of the obtained raw material powder and 58.62 g of lithium carbonate were mixed and fired at 900 ° C. for 20 hours using an electric furnace to obtain a Li-ion battery cathode material. At this time, the temperature rise / fall rate was set at 30 ° C./hr. The battery characteristics were such that the obtained mixture of the positive electrode material: TAB2 = 2: 1 was rolled into a sheet shape using a roller having a gap adjusted to 50 μm, punched out with a 13 mm punch, and used as a positive electrode. Li metal was used for the counter electrode, and 1M-LiPF6 / (EC: DMC = 1: 1) was used for the electrolytic solution. Here, TAB2 is a composite agent of a conductive agent and a binder used for a non-aqueous solution type battery, and is an abbreviation for tephronized door acetylene black (a composite agent of a tetrafluoroethylene binder and acetylene black). The charge and discharge of the battery were performed in the range of 4.3V to 3.0V. Tables 1 and 2 show the physical properties, chemical analysis values, and concentrations of Ni, Co, and Mn in the liquid discharged from the reaction tank of the obtained raw material powder. Tables 3 and 4 show the physical properties, battery characteristics, and chemical analysis values of the fired powder. Although the concentrations of Co and Mn in the liquid discharged from the reaction tank were both 0.01 g / ml or less, the stability of the ammine complex ions of cobalt and manganese was lower than that of nickel ions. In the presence, nickel preferentially exists in the aqueous solution as an ammine complex ion. Since the reaction solution is alkaline, it is considered that cobalt and manganese are almost precipitated as hydroxide particles. Therefore, it is considered that cobalt and manganese hardly dissolved in the reaction solution.
[0020]
As described above, in Example 1, by controlling the pH range to a narrow range (11.4 to 11.7), a raw material hydroxide for a positive electrode material of a lithium ion battery having a high tap density with high productivity can be obtained. . That is, the residence time of the powder in the reaction tank is about 3 hours when calculated from the volume (2.2 l) of the reaction tank and the addition rate of nickel sulfate or the like.
[0021]
[Table 1]
[0022]
[Table 2]
[0023]
[Table 3]
[0024]
[Table 4]
[0025]
Example 2
14.102 kg of nickel sulfate, 15.111 kg of cobalt sulfate, and 12.908 kg of manganese sulfate were dissolved in 80 l of water, and 6 mol / l of sodium hydroxide and aqueous ammonia were used as raw material liquids. FIG. 2 shows a schematic view of the reaction tank. The first stage used a 2.2 liter reaction tank, and the second stage used a 1 liter reaction tank. As in the case of Example 1, the reaction vessel was kept at 40 ° C. by a double jacket in both the first stage and the second stage, and argon gas was bubbled to form a sealed structure. The reaction liquid was stirred using a stirring motor at the first stage at 1000 rpm and at the second stage at 1600 rpm, so that convection as shown in the figure occurred in the reaction tank. Ni, Co, and Mn solutions were supplied to the first-stage reaction vessel at 8 ml / min, an aqueous solution of sodium hydroxide at 4.9 ml / min, and aqueous ammonia at 1.2 ml / min to synthesize the reaction vessel. At this time, the pH in the reaction tank was adjusted to 11.4 to 11.7. The reaction solution is supplied into the second-stage reaction tank. An aqueous sodium hydroxide solution was supplied to the second-stage reaction tank at a rate of 0.5 ml / min, and the pH of the liquid in the reaction tank was adjusted to 12.3 to 12.8. The obtained coprecipitated powder was washed with decantation water, filtered and dried to obtain a raw material powder.
[0026]
The obtained raw material powder (125 g) and lithium carbonate (58.98 g) were mixed and fired at 900 ° C. for 20 hours using an electric furnace to obtain a Li-ion battery cathode material. At this time, the temperature rise / fall rate was set at 30 ° C./hr. The obtained raw material powder and calcined powder were evaluated in the same manner as in Example 1. Tables 1 and 2 show the physical properties, chemical analysis values, and concentrations of Ni, Co, and Mn in the liquid discharged from the reaction tank of the obtained raw material powder. Tables 3 and 4 show the physical properties, battery characteristics, and chemical analysis values of the fired powder.
[0027]
[Example 3]
15.097 kg of nickel sulfate, 13.914 kg of cobalt sulfate, 11.638 kg of manganese sulfate and 398.4 g of magnesium sulfate were dissolved in 80 l of water, and 6 mol / l of sodium hydroxide and aqueous ammonia were used as raw material liquids. Raw material powder was prepared in the same manner as in Example 1.
125 g of the obtained raw material powder and 57.63 g of lithium carbonate were mixed and fired at 900 ° C. for 20 hours using an electric furnace to obtain a positive electrode material for a Li-ion battery. At this time, the temperature rise / fall rate was set at 30 ° C./hr. The obtained raw material powder and calcined powder were evaluated in the same manner as in Example 1. Tables 1 and 2 show the physical properties, chemical analysis values, and concentrations of Ni, Co, and Mn in the liquid discharged from the reaction tank of the obtained raw material powder. Tables 3 and 4 show the physical properties, battery characteristics, and chemical analysis values of the fired powder.
[0028]
[Example 4]
15.097 kg of nickel sulfate, 13.914 kg of cobalt sulfate, 11.638 kg of manganese sulfate, 0.913 l of an aluminum sulfate aqueous solution adjusted to an Al concentration of 1.75 M are dissolved in 80 l of water, and sodium hydroxide 6 mol / l A raw material powder was prepared in the same manner as in Example 1 using ammonia water as a raw material liquid. 125 g of the obtained raw material powder and 57.31 g of lithium carbonate were mixed and fired at 900 ° C. for 20 hours using an electric furnace to obtain a positive electrode material for a Li-ion battery. At this time, the temperature rise / fall rate was set at 30 ° C./hr. The obtained raw material powder and calcined powder were evaluated in the same manner as in Example 1. Tables 1 and 2 show the physical properties, chemical analysis values, and concentrations of Ni, Co, and Mn in the liquid discharged from the reaction tank of the obtained raw material powder. Tables 3 and 4 show the physical properties, battery characteristics, and chemical analysis values of the fired powder.
[0029]
[Example 5]
Example 1 was prepared by dissolving 15.097 kg of nickel sulfate, 13.914 kg of cobalt sulfate, 11.638 kg of manganese sulfate, and 780 g of titanium sulfate in 80 l of water, and using 6 mol / l of sodium hydroxide and aqueous ammonia as a raw material liquid. The raw material powder was prepared in the same manner as in the case of (1).
125 g of the obtained raw material powder and 58.22 g of lithium carbonate were mixed and fired at 900 ° C. for 20 hours using an electric furnace to obtain a positive electrode material for a Li-ion battery. At this time, the temperature rise / fall rate was set at 30 ° C./hr. The obtained raw material powder and calcined powder were evaluated in the same manner as in Example 1. Tables 1 and 2 show the physical properties, chemical analysis values, and concentrations of Ni, Co, and Mn in the liquid discharged from the reaction tank of the obtained raw material powder. Tables 3 and 4 show the physical properties, battery characteristics, and chemical analysis values of the fired powder.
[0030]
[Example 6]
A mixture of 125 g of the raw material powder obtained in Example 1 and 56.92 g of lithium carbonate was fired at 900 ° C. for 20 hours using an electric furnace, and 0.71 g of LiF was added to the obtained powder, followed by firing at 700 ° C. for 10 hours. Thus, a Li-ion battery cathode material was obtained. At this time, the temperature rise / fall rate was set at 30 ° C./hr for the first baking and 140 ° C./hr for the second baking. The obtained raw material powder and calcined powder were evaluated in the same manner as in Example 1. Tables 1 and 2 show the physical properties, chemical analysis values, and concentrations of Ni, Co, and Mn in the liquid discharged from the reaction tank of the obtained raw material powder. Tables 3 and 4 show the physical properties, battery characteristics, and chemical analysis values of the fired powder.
[0031]
[Comparative Example 1]
14.102 kg of nickel sulfate, 15.111 kg of cobalt sulfate, and 12.908 kg of manganese sulfate were dissolved in 80 l of water, and 6 mol / l of sodium hydroxide and aqueous ammonia were used as raw material liquids. The same reactor as that used in Example 1 was used, and the liquid temperature, stirring speed, convection, and nitrogen bubbling were performed under the same conditions. Ni, Co, and Mn solutions were supplied into the reaction tank at a rate of 8 ml / min, an aqueous solution of sodium hydroxide at a rate of 5.5 ml / min, and aqueous ammonia at a rate of 1.2 ml / min. At this time, the pH in the reaction tank was adjusted to 12.3 to 12.8. The obtained coprecipitated powder was washed with decantation water, filtered and dried to obtain a raw material powder.
[0032]
125 g of the obtained raw material powder and 58.08 g of lithium carbonate were mixed and calcined at 1000 ° C. for 20 hours using an electric furnace to obtain a Li-ion battery positive electrode material. At this time, the temperature rise / fall rate was set at 30 ° C./hr. The obtained raw material powder and calcined powder were evaluated in the same manner as in Example 1. Tables 1 and 2 show the physical properties, chemical analysis values, and concentrations of Ni, Co, and Mn in the liquid discharged from the reaction tank of the obtained raw material powder. Tables 3 and 4 show the physical properties, battery characteristics, and chemical analysis values of the fired powder. The raw material synthesized by this method has a high tap density, and the positive electrode material using the raw material as the raw material can also have a high tap density. Table 1 shows the results. According to Table 3, although there was no difference in the discharge capacity per unit weight between the example and the comparative example, it can be seen that the discharge capacity of the high tap density product is excellent when it is per unit volume.
[0033]
【The invention's effect】
As described above, according to the present invention, a raw material hydroxide for a lithium ion battery positive electrode material having a high tap density is obtained, and the lithium ion battery positive electrode material using the raw material hydroxide for the lithium ion battery positive electrode material as a raw material is as follows: It has a high tap density, and when it is used for a lithium ion battery, it is possible to increase the filling amount of the active material in the electrode, and as a result, it is possible to increase the capacity per unit volume.
[Brief description of the drawings]
FIG. 1 is a schematic view of a reaction tank according to the present invention.
FIG. 2 is a schematic view of a reaction tank according to the present invention.
