JP4359744B2 - Active material for positive electrode of secondary battery and manufacturing method thereof - Google Patents
Active material for positive electrode of secondary battery and manufacturing method thereof Download PDFInfo
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- JP4359744B2 JP4359744B2 JP2002028255A JP2002028255A JP4359744B2 JP 4359744 B2 JP4359744 B2 JP 4359744B2 JP 2002028255 A JP2002028255 A JP 2002028255A JP 2002028255 A JP2002028255 A JP 2002028255A JP 4359744 B2 JP4359744 B2 JP 4359744B2
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- 239000011149 active material Substances 0.000 title claims description 16
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- 239000007774 positive electrode material Substances 0.000 claims description 97
- 239000000843 powder Substances 0.000 claims description 68
- 229920005989 resin Polymers 0.000 claims description 33
- 239000011347 resin Substances 0.000 claims description 33
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 28
- 229910052799 carbon Inorganic materials 0.000 claims description 27
- 239000003822 epoxy resin Substances 0.000 claims description 21
- 229920000647 polyepoxide Polymers 0.000 claims description 21
- 239000005011 phenolic resin Substances 0.000 claims description 19
- 229920001187 thermosetting polymer Polymers 0.000 claims description 19
- 239000002131 composite material Substances 0.000 claims description 11
- 230000001590 oxidative effect Effects 0.000 claims description 10
- 239000004593 Epoxy Substances 0.000 claims description 6
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 claims description 4
- 125000003700 epoxy group Chemical group 0.000 claims description 4
- 229920001568 phenolic resin Polymers 0.000 claims description 4
- 238000010000 carbonizing Methods 0.000 claims description 3
- 238000011049 filling Methods 0.000 description 13
- 229910012851 LiCoO 2 Inorganic materials 0.000 description 12
- 238000010438 heat treatment Methods 0.000 description 9
- 229910052744 lithium Inorganic materials 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 6
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 6
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- MHCFAGZWMAWTNR-UHFFFAOYSA-M lithium perchlorate Chemical compound [Li+].[O-]Cl(=O)(=O)=O MHCFAGZWMAWTNR-UHFFFAOYSA-M 0.000 description 1
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- VROAXDSNYPAOBJ-UHFFFAOYSA-N lithium;oxido(oxo)nickel Chemical compound [Li+].[O-][Ni]=O VROAXDSNYPAOBJ-UHFFFAOYSA-N 0.000 description 1
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Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Landscapes
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
Description
【０００１】
【産業上の利用分野】
本発明は、電気伝導性が優れていると共に樹脂への充填性及び分散性が優れている二次電池の正極用活物質に関するものである。
【０００２】
【従来の技術】
近年、パーソナルコンピュ−ター、携帯電話等のポータブル機器の開発に伴って、その電源としての電池の需要が高まっている。特に、リチウム電池は、リチウムが原子量が小さく、かつ、イオン化エネルギーが大きい物質であることに起因して、起電力が高く、高エネルギー密度化が可能な電池が期待できることから各方面で盛んに研究が行われている。
【０００３】
リチウム電池に用いられる正極材粒子粉末としては、４Ｖ程度の高電圧を発生させることが可能なリチウムコバルト酸化物（ＬｉＣｏＯ2）粒子粉末、リチウムニッケル酸化物（ＬｉＮｉＯ2）粒子粉末、リチウムマンガンスピネル酸化物（Ｌｉ1+XＭｎ2-XＯ4）粒子粉末等、リチウム複合酸化物粒子の研究が盛んに行われている。これらの正極材粒子粉末は、コバルト、ニッケル、マンガンを含む酸化物原料粉末とリチウム化合物粉末とを混合し、５００℃以上の高温で焼成することにより得られている。
【０００４】
電池の小型化、高性能化に伴って電極材料である正極材粒子粉末の特性向上もまた強く要求されている。
即ち、上記正極材粒子粉末は、体積固有抵抗値が通常１０5Ωｃｍ程度と高いため、高い電気伝導性を有する正極材粒子粉末が強く要求されている。
【０００５】
次に、上記正極材粒子粉末を用いて電極を製造する場合、正極材粒子粉末とポリフッ化ビニリデン（ＰＶＤＦ)やポリテトラフルオロエチレン（ＰＴＦＥ）等の結着材と溶剤とを混練し得られるペーストを集電体であるニッケルのメッシュに塗工して電極とするが、二次電池の充放電容量を高めるためには正極材粒子粉末の樹脂への充填性及び分散性ができるだけ優れていることが強く要求されている。
【０００６】
従来、正極材粒子粉末の電気伝導性を高める方法としては、
▲１▼ケッチェンブラックやアセチレンブラック等のカーボン材料をメカノケミカル法により、正極材粒子粉末の表面に付着させることにより導電剤層を形成させる方法（特開平９−９２２６５号公報や特開平１０−１６２８２５号公報、特開平１１−５４１４８号公報、特開平１１−２８３６２３号公報、特開２００１−２５０５５３号公報等）、
▲２▼正極材粒子粉末の粒子表面に炭素、Ａｕ、Ｎｉ等の金属を蒸着させる方法（特開平１１−３０７０８３号公報等）、
▲３▼正極材粒子粉末と該正極材粒子粉末に対し５０重量％程度の多量の有機物とを混合した後、混練物を解砕し、さらに熱処理することで有機物を炭化させる方法（特開２０００−２５１８８８号公報）等が知られている。
【０００７】
【発明が解決しようとする課題】
電気伝導性が優れていると共に樹脂への充填性及び分散性が優れている正極材粒子粉末は、現在最も要求されているところであるが、未だこれら諸特性を満足する正極用活物質は得られていない。
【０００８】
即ち、前出▲１▼の正極材粒子粉末は、機械的な衝撃でカーボン等を正極材粒子粉末の粒子表面に付着させただけの構造であるため、電極を製造する際に付着しているカーボンが脱離してしまうという問題がある。即ち、表面にカーボンが付着している正極材粒子粉末と結着材と溶剤とを混練して混練物を製造する際にカーボンは容易に正極材粒子粉末の粒子表面から脱離してしまい、電気伝電度を高める効果が不十分となり、長期間の使用においても安定した電気伝導度を得ることが困難となる。また、脱離したカーボンが正極材粒子粉末の樹脂への充填性及び分散性を防げることとなる。
【０００９】
前出▲２▼の正極材粒子粉末も上記▲１▼と同様に、結着材及び溶剤との混練の際に正極材粒子粉末の粒子表面から蒸着金属が脱離してしまい、電気伝導度を高める効果が不十分となり、長期間の使用においても安定した充放電特性を得ることが困難となる。
【００１０】
前出▲３▼の正極材粒子粉末は、正極材粒子粉末に対する樹脂の量が多量であるため正極材粒子と有機物とを混合した際に凝集物となり、これを解砕しても、混合する前の正極材粒子粉末の大きさまで解砕されないため、樹脂への充填率があまり高くならず、充電容量が不十分であるという問題がある。
【００１１】
そこで、本発明は、電気伝導度が優れていると共に樹脂への充填性及び分散性が優れている正極材粒子粉末を得ることを技術的課題とする。
【００１２】
【課題を解決する為の手段】
前記技術的課題は、次の通りの本発明によって達成できる。即ち、本発明は、正極材粒子の粒子表面に、熱硬化性フェノール樹脂又は熱硬化性エポキシ樹脂を酸化雰囲気下で熱処理して得られるカーボンが被覆されている複合正極材粒子からなる複合正極材粒子粉末であって、前記複合正極材粒子粉末のタップ密度が２．０ｇ／ｍｌ以上であり、カーボン量が正極材粒子に対し０．０１〜１．０重量％であることを特徴とする二次電池の正極用活物質である。(発明１)
【００１３】
また、本発明は、熱硬化性フェノール樹脂のＯＨ当量が１３０ｇ／当量以上の熱硬化性フェノール樹脂であることを特徴とする発明１記載の二次電池の正極用活物質である。（発明２)
【００１４】
また、本発明は、熱硬化性エポキシ樹脂が１分子中に２個以上のエポキシ基を有し、エポキシ当量が２００g／当量以上の熱硬化性エポキシ樹脂であることを特徴とする発明１記載の二次電池の正極用活物質である。（発明３)
【００１５】
また、本発明は、正極材粒子粉末に該正極材粒子粉末に対し０.０１〜１０重量％の熱硬化性フェノール樹脂又は熱硬化性エポキシ樹脂を被覆した後、酸化雰囲気下、４００℃以上の温度で熱処理して前記樹脂を炭化させることにより複合正極材粒子粉末を得ることを特徴とする発明１乃至発明３のいずれかに記載の二次電池の正極用活物質の製造方法である。（発明４)
【００１６】
本発明の構成をより詳しく説明すれば、次の通りである。
【００１７】
本発明における芯粒子である正極材粒子粉末は、ＬｉXＭyＯ2（但し、ＭはＣｏ，Ｎｉ，Ｍｎ，Ｖ，Ｆｅ及びＴｉから選ばれた１種又は２種以上の元素、ｘは０＜ｘ≦２.５の範囲であり、ｙは０.８≦ｙ≦１.２５の範囲である。）で示される複合金属酸化物粒子粉末を示す。
【００１８】
正極材粒子粉末の粒子形態は、立方体状、多面体状、球状、針状、板状等のいずれの形態の粒子をも使用することができる。
正極材粒子粉末の充填量及び分散性を考慮すると球状粒子が好ましく、集電体に塗工する際のペーストの粘度を下げることができる。
【００１９】
正極材粒子粉末の平均粒子径Ｄ50（正極材粒子粉末の全体積を１００％として累積体積で表した粒子径を求めたときの累積割合が５０％となる点）は、樹脂への充填性及び分散性や取り扱い等の作業性を考慮すると、０.５〜５０μｍであることが好ましく、より好ましくは０.５〜４０μｍ、更に好ましくは０.５〜３０μｍである。
【００２０】
本発明に係る二次電池の正極用活物質におけるカーボンは、正極材粒子の粒子表面に強固に固着して粒子表面の全部又は一部を被覆している。
【００２１】
カーボン量は、芯粒子に対し０.０１〜１０重量％、より好ましくは０.０２〜３重量％、更に好ましくは０.０２〜１重量％である。
０.０１重量％未満の場合には、得られる正極用活物質の電気伝導度を高める効果が不十分となる。
１０重量％を超える場合には、得られる正極用活物質の樹脂への充填性及び分散性が不十分となる。
【００２２】
本発明に係る二次電池の正極活物質は、好ましくは体積固有抵抗値が１×１０2〜９×１０4Ωｃｍである。
９×１０4Ωｃｍを超える場合には、電気伝導度を高める効果が不十分であるため、二次電池としての充放電容量を高めることが困難となる。体積固有抵抗値の下限値は１×１０2Ωｃｍである。更に、電気伝導度を高める場合には、カーボン量を芯粒子に対して１０重量％を超えて被覆する必要があり、その結果、正極用活物質の充填量が低下する。
【００２３】
本発明に係る正極用活物質は、好ましくはタップ密度が２.０ｇ／ｍｌ以上、より好ましくは２.１ｇ／ｍｌ以上である。その上限は３.０ｇ／ｍｌが好ましい。
２.０ｇ／ｍｌ未満の場合には、樹脂への充填量を高くすることが困難となる。
【００２４】
本発明に係る二次電池の正極用活物質は、電極化する上で樹脂への分散性が優れていることが好ましく、平均粒子径及び粒度分布を調整することが好ましい。即ち、本発明に係る二次電池の正極用活物質の平均粒子径Ｄ50は、１〜５０μｍ、より好ましくは１〜４０μｍ、更に好ましくは１〜３０μｍである。
【００２５】
本発明に係る二次電池の正極用活物質の平均粒子径Ｄ10は、０.５〜５.０μｍ、より好ましくは０.６〜４.８μｍ、更に好ましくは０.７〜４.６μｍである。
【００２６】
本発明に係る二次電池の正極用活物質の平均粒子径Ｄ90は、３.０〜２８.０μｍ、より好ましくは３.２〜２６.０μｍ、更に好ましくは３.５〜２５.０μｍである。
【００２７】
本発明に係る二次電池の正極用活物質の粒度分布は、Ｄ50で示した場合の平均粒子径に対するＤ90（正極材粒子粉末の全体積を１００％として累積体積で表した粒子径を求めたときの累積割合が９０％となる点）で示した場合の平均粒子径の比率（Ｄ90／Ｄ50）で、好ましくは３.０以下、より好ましくは２.８以下である。Ｄ10（正極材粒子粉末の全体積を１００％として累積体積で表した粒子径を求めたときの累積割合が１０％となる点）で示した場合の平均粒子径に対するＤ50で示した場合の平均粒子径の比率（Ｄ50／Ｄ10）で、好ましくは３.０以下、より好ましくは２.５以下である。
【００２８】
本発明に係る正極用活物質の比表面積は、電極化を考慮すると０.２〜２０ｍ2／ｇであることが好ましく、より好ましくは０.２〜１５ｍ2／ｇ、更に好ましくは０.２〜１０ｍ2／ｇの範囲である。
【００２９】
次に、本発明に係る二次電池の正極用活物質の製造方法について述べる。
【００３０】
本発明に係る二次電池の正極用活物質は、正極材粒子粉末に熱硬化性フェノール樹脂又は熱硬化性エポキシ樹脂を被覆した後、酸化性雰囲気下で熱処理することにより製造することができる。
【００３１】
先ず、正極材粒子の粒子表面に樹脂を十分且つ均一に被覆することが必要である。
【００３２】
フェノール樹脂としては、フェノールとホルマリンのモル比で１／１〜１／３の範囲にある、いわゆるレゾ−ル系のフェノール樹脂が望ましい。
ＯＨ当量が１３０ｇ／当量以上の熱硬化性フェノール樹脂が望ましく、より好ましくは１５０ｇ／当量以上、更に好ましくは１８０ｇ／当量以上であり、上限値は３００ｇ／当量が好ましい。
１３０ｇ／当量未満の場合には、樹脂による被覆処理の際に正極材粒子同士の凝集が生じやすく、その結果、得られる正極用活物質は樹脂への充填性及び分散性が困難となる。
【００３３】
本発明におけるエポキシ樹脂としては、１分子中に２個以上のエポキシ基を有するエポキシ樹脂が好ましく、具体的には、ビスフェノールＡ型エポキシ樹脂、ノボラック型エポキシ樹脂、ハロゲン化エポキシ樹脂、グリシジルエステル型エポキシ樹脂などが用いられる。エポキシ基が２個未満の場合には、正極材粒子の粒子表面への樹脂の被覆が困難となる。
【００３４】
エポキシ樹脂は、エポキシ当量として２００ｇ/当量以上のものが好ましく、より好ましくは、２００−５００ｇ/当量である。
エポキシ当量が２００ｇ／当量未満の場合には、正極材粒子の粒子表面への樹脂の被覆処理の際に粒子同士の凝集が生じやすく、結果として、得られる正極用活物質は樹脂への充填性及び分散性が困難となる。
【００３５】
本発明における樹脂の被覆量は、正極材粒子粉末に対して０.１〜１０重量％が好ましく、より好ましくは０.５〜５重量％である。
０.１重量％未満の場合には、被覆するフェノール樹脂あるいはエポキシ樹脂の量が正極材粒子に対して不十分となるために、得られる正極用活物質の電気伝導度を高める効果が不十分となる。
１０重量％を越える場合には、正極材粒子同士が凝集してしまい、得られる正極用活物質は樹脂への充填量を高くできない。
【００３６】
樹脂による正極材粒子粉末の被覆処理は、正極材粒子粉末と樹脂と若干の溶剤とをハイスピードミキサー（深江パウテック(株)製）、ヘンシェルミキサー（三井三池(株)製）、ＣＦグラニュレーター（フロイント産業(株)製）、バーチカル・グラニュレーター（(株)パウレック製）、フロージェットグラニュレーター（(株)大川原製作所製）、万能攪拌機（(株)ダルトン製）、ナウタミキサー（(株)ホソカワミクロン製）等のいわゆる攪拌機能を有した処理機を用いて攪拌すればよい。
【００３７】
本発明の目的とする正極用活物質を得ることができれば、必ずしも正極材粒子の全表面が樹脂によって被覆されている必要はなく、部分的に被覆されていてもよい。正極材粒子間の凝集を防止するためには、ヘンシェルミキサーのような高速攪拌機での処理が好ましい。
【００３８】
次に、粒子表面が樹脂で被覆されている上記正極材粒子粉末を、酸化雰囲気下で熱処理することにより樹脂の炭化を行う。
酸化雰囲気にするためには、空気を熱処理炉内に流せばよく、通常１ ｌ／ｍｉｎ以上流すことで十分である。
【００３９】
不活性雰囲気下で熱処理を行うと、正極材粒子が有しているＬｉ+が還元されることによって、正極材粒子の組成自体が変化してしまい、電池特性に悪影響を与えるので、本発明においては酸化雰囲気下で加熱することが肝要である。
【００４０】
熱処理温度としては、４００℃以上であり、好ましくは４００〜１０００℃の範囲であり、より好ましくは４００〜８００℃の範囲である。１０００℃を越える場合には、正極材粒子の組成自体が変化してしまい、電池特性に悪影響を与える。一方、４００℃未満である場合には、樹脂が十分に炭化されず、正極材粒子の電気伝導度を高めることができない。
【００４１】
使用する熱処理機としては、固定式のものや、回転式のもの等いずれでもよいが、粒子同士の凝集を防ぐためには、回転式のものが好ましい。
【００４２】
熱処理を行う時間は、０.５〜４時間の処理で十分である。
【００４３】
【発明の実施の形態】
本発明の代表的な実施の形態は次の通りである。
【００４４】
尚、以下の実施の形態及び後出実施例並びに比較例における平均粒子径（Ｄ10 、Ｄ50及びＤ90）は、レーザー回折式粒度分布計（ＳＹＭＰＡＴＥＣ社製ＲＯＤＯＳ）により計測した値で示した。
【００４５】
カーボン量は、カーボン溶出テストを用いて測定した値で示した。
１００ｍｌガラス製サンプル瓶中に、溶剤としてのＮ−メチル−２−ピロリドン（以下、ＮＭＰと略す。）１００ｍｌと正極材粒子各２ｇを加え、手振りで５０回振とうさせた後、５分間静置させる。上澄み液の透過度をＵＶ測定器（ＵＶ-２４００ＰＣ；島津製作所製）を用いて６００ｎｍ波長の吸収で評価した。
透過度が８０％以上 良
６０％〜８０％ 可
６０％未満 不可
正極材粒子表面からカーボンが容易に脱離する場合には透過度は低く、一方、しっかりと正極材粒子表面に被覆されているものでは、透過度は高い。
【００４６】
体積固有抵抗値は、ホィーストンブリッジ２７６８（横河電機(株)製）を用いて測定した。
【００４７】
ＢＥＴ比表面積は、窒素吸着法により測定した。
【００４８】
正極材粒子の同定及びその結晶構造の解析は、Ｘ線回折（ＲＩＧＡＫＵ，Ｍｎ−ｆｉｌｔｅｒｅｄ Ｆｅ−Ｋα、４０ｋＶ ａｎｄ ２０ｍＡ）により行った。
【００４９】
電極活物質の電気化学特性は、ポテンシャルスイーブ法により評価した。測定用正極電極として種々の正極材粒子粉末と、バインダーとしてポリテトラフルオロエチレン、導電材としてケッチェンブラックを各々重量比で５％混合し、この混合物を０.５ｇ秤量し、集電体としてのニッケルのメッシュに充填し、作用電極とした。負極電極として金属リチウム箔をステンレス鋼メッシュに充填した。更に参照電極としてはリチウム金属を用いた。過塩素酸リチウム（LiClO4）を、プロピレンカルボネート、ジメトキシエタンを体積比で１：１に混合した溶媒中に１Ｍの濃度で溶解させたものを電解質として用いた。
【００５０】
以上の測定用正極作用電極、負極、参照電極、電解質を用いて電気化学測定セルを構成した。この電気化学セルを用い、金属リチウム電極基準で３.０〜４.２Ｖの測定範囲、電流０.５ｍＡ／ｃｍ2にて充放電曲線を調べた。
【００５１】
＜正極用活物質の製造＞
ヘンシェルミキサー内にＬｉＣｏＯ2粒子粉末（平均粒径４.０μｍ、体積固有抵抗２.２×１０5Ωｃｍ タップ密度２.４２ｇ／ｍｌ）１ｋｇを仕込み、窒素ガスを1 ｌ/ｍｉｎで流しながら、９６０ｒｐｍで攪拌を行い、続いて、ＯＨ当量が１８５ｇ／当量であるレゾール型フェノール樹脂「フェノライトＪ−３２５」（商品名：大日本インキ化学工業(株)）８.３ｇ及びエタノール１０ｇを添加した。
粉体温度が７０℃になるように加温し、約２時間攪拌した後、冷却することで上記ＬｉＣｏＯ2粒子粉末の粒子表面を０.４９重量％のフェノール樹脂で被覆処理した。
【００５２】
次に、得られたフェノール樹脂が被覆されているＬｉＣｏＯ2粒子粉末を、回転式熱処理炉内に入れ、空気を１ ｌ／ｍｉｎの流量で流しながら、品温が５００℃まで９０分間で昇温し、５００℃で１時間保持を樹脂の炭化を行ってカーボンが被覆されているＬｉＣｏＯ2粒子粉末を製造した後、５０℃以下の温度まで冷却して複合正極材粒子粉末（Ａ）を取り出した。
【００５３】
得られた複合正極材粒子粉末（Ａ）の平均粒子径は、Ｄ50で示した場合４.２μｍ、Ｄ10で示した場合、２.０μｍ、Ｄ90で示した場合、１０.５μｍであり、（Ｄ90／Ｄ50）比率が２.５であって、（Ｄ50／Ｄ10）比率が２.１であり、比表面積が１.０ｍ2／ｇ、体積固有抵抗が２×１０4Ωｃｍ、タップ密度が２.５０、カーボン量が０.０４％、カーボン溶出テストは（良）であった。
さらに、この充放電の電気容量を求めたところ、１６２ｍＡｈ／ｇであった。
なお、比較の為、前記ＬｉＣｏＯ2粒子粉末を樹脂で被覆することなくそのまま使用した場合の電気容量は１５７ｍＡｈ／ｇであった。
【００５４】
【作用】
本発明において最も重要な点は、粒子表面にフェノール樹脂又はエポキシ樹脂が被覆されている正極材粒子を酸化雰囲気下で熱処理した場合には、カーボンが被覆されている正極材粒子を得ることができ、該カーボンは容易に脱離しないため、電気伝導性を高めることができ、長期間の使用においても安定して電気伝導性を高めることができるという事実である。
【００５５】
正極材粒子の粒子表面からカーボンが脱離しにくい理由について、本発明者は、正極材粒子の粒子表面を特定のフェノール樹脂又はエポキシ樹脂で被覆した後に、酸化雰囲気下で熱処理して樹脂を炭化したものであることに起因して、カーボンがしっかりと正極材粒子表面に固定されているものと考えている。
【００５６】
そして、本発明に係る二次電池の正極用活物質は粒度分布が優れているので、正極用活物質の樹脂への充填量を高めることが可能であるという事実である。
【００５７】
【実施例】
次に、実施例及び比較例を挙げる。
【００５８】
実施例１
前記発明の実施の形態と同様にして、ＬｉＣｏＯ2粒子粉末（平均粒子径１.２μｍ、体積固有抵抗値３.５×１０5Ωｃｍ）１ｋｇをエポキシ当量が３００ｇ／当量であるエポキシ樹脂「エピクロン５３００−７０」（商品名：大日本インキ化学工業(株)製）２１ｇおよびメタノール４０ｇの混合溶液で表面処理を行った。粉体温度が７０℃になるように加温し、約２時間攪拌した後、冷却することで、ＬｉＣｏＯ2の粒子表面をエポキシ樹脂で被覆処理した粒子粉末を得た。
【００５９】
次に、得られたエポキシ樹脂が被覆されているＬｉＣｏＯ2粒子粉末を、回転式熱処理炉内に入れ、空気を１ ｌ／ｍｉｎの流量で流しながら、品温が６００℃まで２時間で昇温し、６００℃で１時間保持を行った後、５０℃以下の温度まで冷却を行い取り出した。
この時の主要製造条件を表１に、得られたＬｉＣｏＯ2粒子粉末（Ｂ）の諸特性を表２に示す。
【００６０】
実施例２〜６、比較例１〜５
正極材粒子粉末の種類、被覆する樹脂の種類及び量、熱処理条件を種々変化させた以外は、前記発明の実施の形態と同様にしてカーボンが被覆されている被覆正極材粒子粉末の生成を行った。主要製造条件を表１に、及び諸特性を表２に示す。
【００６１】
比較例６
ＬｉＮｉＯ2粒子粉末（平均粒子径１.５μｍ、体積固有抵抗４.２×１０5Ωｃｍ）３００ｇとケッチェンブラック「ＥＣＰ−６００ＪＤ」（商品名：ライオン(株)製）４.５ｇをメカノフュージョン装置「ＡＭ−１５Ｆ」（商品名：ホソカワミクロン製）を用いて3０分間処理を行った。
この時の主要製造条件を表１に、得られた粒子表面にカーボンが付着しているＬｉＮｉＯ2粒子粉末（Ｍ）の特性を表２に示す。
【００６２】
比較例７
ＬｉＣｏＯ2粒子粉末（平均粒径４.０μｍ、体積固有抵抗値２.２×１０5Ωｃｍ）１ｋｇとＯＨ当量１００ｇ／当量であるノボラック型フェノール樹脂「タマノル１００Ｓ」（商品名：荒川化学工業(株)）２０ｇをエクスルーダーで混練した後、粉砕・分級して複合体粒子を製造した。得られた複合体粒子粉末は、平均粒子径が１８.２μｍであった。得られた複合体粒子粉末を、回転式熱処理炉内に入れ、空気を１ ｌ／ｍｉｎの流量で流しながら、品温が５００℃まで９０分間で昇温し、５００℃で１時間保持を行った後、５０℃以下の温度まで冷却を行い取り出した。
【００６３】
得られた粒子表面にカーボンが被覆されているＬｉＣｏＯ2粒子粉末（Ｎ）の特性を表２に示す。
【００６４】
【表１】
【表２】
【発明の効果】
本発明に係る二次電池の正極用活物質は、正極材粒子の粒子表面にしっかりとカーボンが被覆されているため、正極を調整する際のストレスによっても粒子表面から容易に脱離せず、電気伝導度が優れているとともに、樹脂への充填性及び分散性が優れているので、二次電池の正極用活物資として好適である。
【００６７】
そして、上記正極用活物質を用いた場合には、二次電池の充放電容量を高めることができる。[0001]
[Industrial application fields]
The present invention relates to an active material for a positive electrode of a secondary battery having excellent electrical conductivity and excellent filling and dispersibility in a resin.
[0002]
[Prior art]
In recent years, with the development of portable devices such as personal computers and mobile phones, the demand for batteries as power sources has increased. In particular, lithium batteries are actively researched in various fields because lithium is a substance with a low atomic weight and high ionization energy, and a battery with high electromotive force and high energy density can be expected. Has been done.
[0003]
The positive electrode material powder used in the lithium battery includes lithium cobalt oxide (LiCoO 2 ) particle powder, lithium nickel oxide (LiNiO 2 ) particle powder, and lithium manganese spinel oxidation capable of generating a high voltage of about 4V. Research on lithium composite oxide particles such as product (Li 1 + X Mn 2−X O 4 ) particle powder has been actively conducted. These positive electrode material particle powders are obtained by mixing an oxide raw material powder containing cobalt, nickel, and manganese and a lithium compound powder and firing them at a high temperature of 500 ° C. or higher.
[0004]
With the miniaturization and high performance of batteries, there is also a strong demand for improving the characteristics of positive electrode material particle powder as an electrode material.
That is, since the positive electrode material particle powder has a high volume resistivity of about 10 5 Ωcm, which is usually about 10 5 Ωcm, there is a strong demand for positive electrode material particle powder having high electrical conductivity.
[0005]
Next, when manufacturing an electrode using the positive electrode material particle powder, a paste obtained by kneading the positive electrode material particle powder, a binder such as polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE), and a solvent. In order to increase the charge / discharge capacity of the secondary battery, the chargeability and dispersibility of the positive electrode material powder in the resin must be as excellent as possible. Is strongly demanded.
[0006]
Conventionally, as a method for increasing the electrical conductivity of the positive electrode material particle powder,
(1) A method of forming a conductive agent layer by attaching a carbon material such as ketjen black or acetylene black to the surface of the positive electrode material particle powder by a mechanochemical method (Japanese Patent Laid-Open Nos. 9-92265 and 10- 162825, JP-A-11-54148, JP-A-11-283623, JP-A-2001-250553, etc.),
(2) A method of depositing a metal such as carbon, Au, or Ni on the particle surface of the positive electrode material particle powder (JP-A-11-307083, etc.)
(3) A method of carbonizing the organic material by mixing the positive electrode material particle powder and a large amount of organic substance of about 50% by weight with respect to the positive electrode material particle powder, pulverizing the kneaded material, and further heat-treating (Japanese Patent Laid-Open No. 2000) -251888) and the like are known.
[0007]
[Problems to be solved by the invention]
A positive electrode particle powder that has excellent electrical conductivity and excellent resin filling and dispersibility is currently the most demanded, but a positive electrode active material that still satisfies these characteristics can still be obtained. Not.
[0008]
That is, since the positive electrode material particle powder (1) has a structure in which carbon or the like is simply adhered to the particle surface of the positive electrode material particle powder by mechanical impact, it adheres when the electrode is manufactured. There is a problem that carbon is desorbed. That is, when producing a kneaded product by kneading the positive electrode material particle powder with the carbon adhering to the surface, the binder, and the solvent, the carbon is easily detached from the surface of the positive electrode material particle powder. The effect of increasing the electrical conductivity becomes insufficient, and it becomes difficult to obtain a stable electrical conductivity even during long-term use. Further, the desorbed carbon can prevent filling and dispersibility of the positive electrode material particle powder into the resin.
[0009]
Similarly to the above (1), the positive electrode material particle powder of the above (2) is detached from the surface of the positive electrode material particle powder during kneading with the binder and the solvent, and the electric conductivity is reduced. The effect of increasing becomes insufficient, and it becomes difficult to obtain stable charge / discharge characteristics even after long-term use.
[0010]
The positive electrode material particle powder of the above (3) becomes agglomerates when the positive electrode material particles and the organic substance are mixed because the amount of the resin with respect to the positive electrode material particle powder is large, and is mixed even if pulverized. Since it is not crushed to the size of the previous positive electrode material particle powder, there is a problem that the filling rate into the resin is not so high and the charging capacity is insufficient.
[0011]
Then, this invention makes it a technical subject to obtain the positive electrode material particle powder which is excellent in electrical conductivity, and is excellent in the filling property and dispersibility to resin.
[0012]
[Means for solving the problems]
The technical problem can be achieved by the present invention as follows. That is, the present invention provides a composite positive electrode material comprising composite positive electrode material particles in which the surface of the positive electrode material particles is coated with carbon obtained by heat-treating a thermosetting phenol resin or a thermosetting epoxy resin in an oxidizing atmosphere. What particles der, the composite tap density of the positive electrode material particles is at 2.0 g / ml or more, the amount of carbon and wherein 0.01 to 1.0 wt% der Rukoto to particulate positive electrode material The active material for the positive electrode of the secondary battery. (Invention 1)
[0013]
The present invention is also the active material for a positive electrode of the secondary battery according to invention 1, wherein the thermosetting phenol resin is a thermosetting phenol resin having an OH equivalent of 130 g / equivalent or more. (Invention 2)
[0014]
Further, the present invention is the thermosetting epoxy resin according to the invention 1, wherein the thermosetting epoxy resin has two or more epoxy groups in one molecule, and the epoxy equivalent is 200 g / equivalent or more. It is an active material for a positive electrode of a secondary battery. (Invention 3)
[0015]
Further, in the present invention, the positive electrode material particle powder is coated with 0.01 to 10% by weight of thermosetting phenol resin or thermosetting epoxy resin with respect to the positive electrode material particle powder, and then is heated to 400 ° C. or higher in an oxidizing atmosphere. 4. The method for producing an active material for a positive electrode of a secondary battery according to claim 1, wherein the composite positive electrode material particle powder is obtained by carbonizing the resin by heat treatment at a temperature. (Invention 4)
[0016]
The configuration of the present invention will be described in more detail as follows.
[0017]
Positive electrode material particles as core particles in the present invention, Li X M y O 2 (where, M is at least one element selected Co, Ni, Mn, V, Fe and Ti, x is 0 <x ≦ 2.5, and y is in the range of 0.8 ≦ y ≦ 1.25.)
[0018]
As the particle form of the positive electrode material particle powder, any form of particles such as a cubic shape, a polyhedral shape, a spherical shape, a needle shape, and a plate shape can be used.
In consideration of the filling amount and dispersibility of the positive electrode material particle powder, spherical particles are preferable, and the viscosity of the paste when applied to the current collector can be lowered.
[0019]
The average particle diameter D 50 of the positive electrode material particle powder (the point at which the cumulative ratio when the particle diameter expressed by the cumulative volume is 100% with the total volume of the positive electrode material powder being 100%) is 50%. In consideration of workability such as dispersibility and handling, the thickness is preferably 0.5 to 50 μm, more preferably 0.5 to 40 μm, and still more preferably 0.5 to 30 μm.
[0020]
The carbon in the positive electrode active material of the secondary battery according to the present invention firmly adheres to the particle surface of the positive electrode material particles and covers all or part of the particle surface.
[0021]
The amount of carbon is 0.01 to 10% by weight, more preferably 0.02 to 3% by weight, still more preferably 0.02 to 1% by weight, based on the core particles.
When the amount is less than 0.01% by weight, the effect of increasing the electrical conductivity of the obtained positive electrode active material becomes insufficient.
When it exceeds 10% by weight, the filling property and dispersibility of the obtained positive electrode active material into the resin are insufficient.
[0022]
The positive electrode active material of the secondary battery according to the present invention preferably has a volume resistivity value of 1 × 10 2 to 9 × 10 4 Ωcm.
When it exceeds 9 × 10 4 Ωcm, it is difficult to increase the charge / discharge capacity of the secondary battery because the effect of increasing the electrical conductivity is insufficient. The lower limit value of the volume resistivity is 1 × 10 2 Ωcm. Furthermore, when increasing the electrical conductivity, it is necessary to coat the carbon in an amount exceeding 10% by weight with respect to the core particles, and as a result, the filling amount of the positive electrode active material decreases.
[0023]
The positive electrode active material according to the present invention preferably has a tap density of 2.0 g / ml or more, more preferably 2.1 g / ml or more. The upper limit is preferably 3.0 g / ml.
If it is less than 2.0 g / ml, it is difficult to increase the filling amount of the resin.
[0024]
The positive electrode active material of the secondary battery according to the present invention is preferably excellent in dispersibility in the resin when converted into an electrode, and it is preferable to adjust the average particle size and the particle size distribution. That is, the average particle diameter D 50 of the positive electrode active material of the secondary battery according to the present invention is 1 to 50 μm, more preferably 1 to 40 μm, and still more preferably 1 to 30 μm.
[0025]
The average particle diameter D 10 of the positive electrode active material of the secondary battery according to the present invention is 0.5 to 5.0 μm, more preferably 0.6 to 4.8 μm, and still more preferably 0.7 to 4.6 μm. is there.
[0026]
The average particle diameter D 90 of the positive electrode active material of the secondary battery according to the present invention is 3.0 to 28.0 μm, more preferably 3.2 to 26.0 μm, still more preferably 3.5 to 25.0 μm. is there.
[0027]
The particle size distribution of the active material for the positive electrode of the secondary battery according to the present invention is D 90 with respect to the average particle size in the case of D 50 (the particle size expressed in cumulative volume with the total volume of the positive electrode material powder being 100%. The average particle size ratio (D 90 / D 50 ) in the case where the cumulative ratio is 90% when obtained) is preferably 3.0 or less, more preferably 2.8 or less. D 10 case shown by the average D 50 to particle size in the case shown in (a cumulative percentage of the time of obtaining the particle diameter expressed in cumulative volume on the total volume of the positive electrode material particles as 100% is a point 10%) The average particle size ratio (D 50 / D 10 ) is preferably 3.0 or less, more preferably 2.5 or less.
[0028]
The specific surface area of the positive electrode active material according to the present invention is preferably 0.2~20m 2 / g considering the electroded, more preferably 0.2~15m 2 / g, more preferably 0.2 It is the range of -10m < 2 > / g.
[0029]
Next, the manufacturing method of the active material for positive electrodes of the secondary battery which concerns on this invention is described.
[0030]
The positive electrode active material of the secondary battery according to the present invention can be produced by coating the positive electrode material particle powder with a thermosetting phenol resin or a thermosetting epoxy resin and then heat-treating it in an oxidizing atmosphere.
[0031]
First, it is necessary to coat the surface of the positive electrode material particles sufficiently and uniformly with the resin.
[0032]
As the phenolic resin, a so-called resole phenolic resin having a molar ratio of phenol to formalin of 1/1 to 1/3 is desirable.
A thermosetting phenol resin having an OH equivalent of 130 g / equivalent or more is desirable, more preferably 150 g / equivalent or more, still more preferably 180 g / equivalent or more, and the upper limit is preferably 300 g / equivalent.
When the amount is less than 130 g / equivalent, the positive electrode material particles tend to aggregate during the coating treatment with the resin, and as a result, the resulting positive electrode active material is difficult to fill and disperse in the resin.
[0033]
The epoxy resin in the present invention is preferably an epoxy resin having two or more epoxy groups in one molecule, and specifically, bisphenol A type epoxy resin, novolac type epoxy resin, halogenated epoxy resin, glycidyl ester type epoxy. Resin or the like is used. When the number of epoxy groups is less than 2, it is difficult to coat the resin on the surface of the positive electrode material particles.
[0034]
The epoxy resin preferably has an epoxy equivalent of 200 g / equivalent or more, more preferably 200-500 g / equivalent.
When the epoxy equivalent is less than 200 g / equivalent, the particles are likely to agglomerate during the resin coating process on the surface of the positive electrode material particles. As a result, the obtained positive electrode active material has a resin filling property. And dispersibility becomes difficult.
[0035]
The coating amount of the resin in the present invention is preferably from 0.1 to 10% by weight, more preferably from 0.5 to 5% by weight, based on the positive electrode material particle powder.
When the amount is less than 0.1% by weight, the amount of phenol resin or epoxy resin to be coated is insufficient with respect to the positive electrode material particles, so that the effect of increasing the electric conductivity of the obtained positive electrode active material is insufficient. It becomes.
When the amount exceeds 10% by weight, the positive electrode material particles are aggregated, and the obtained positive electrode active material cannot increase the filling amount of the resin.
[0036]
The coating treatment of the positive electrode material particle powder with the resin is performed by combining the positive electrode material particle powder, the resin, and some solvent with a high speed mixer (Fukae Powtech Co., Ltd.), Henschel mixer (Mitsui Miike Co., Ltd.), CF granulator ( Freund Sangyo Co., Ltd.), Vertical Granulator (Powrec Co., Ltd.), Flow Jet Granulator (Okawara Seisakusho Co., Ltd.), Universal Stirrer (Dalton Co., Ltd.), Nauta Mixer (Hosokawa Micron Co., Ltd.) It is only necessary to stir using a processing machine having a so-called stirring function, such as a manufactured product.
[0037]
As long as the positive electrode active material that is the object of the present invention can be obtained, the entire surface of the positive electrode material particles does not necessarily have to be coated with the resin, and may be partially coated. In order to prevent aggregation between the positive electrode material particles, treatment with a high-speed stirrer such as a Henschel mixer is preferable.
[0038]
Next, the positive electrode material particle powder whose particle surface is coated with resin is heat-treated in an oxidizing atmosphere to carbonize the resin.
In order to obtain an oxidizing atmosphere, it is sufficient to flow air into the heat treatment furnace, and it is usually sufficient to flow at 1 l / min or more.
[0039]
When heat treatment is performed in an inert atmosphere, the composition of the positive electrode material particles itself is changed by reducing Li + contained in the positive electrode material particles, which adversely affects battery characteristics. It is important to heat in an oxidizing atmosphere.
[0040]
As heat processing temperature, it is 400 degreeC or more, Preferably it is the range of 400-1000 degreeC, More preferably, it is the range of 400-800 degreeC. When the temperature exceeds 1000 ° C., the composition of the positive electrode material particles changes, which adversely affects the battery characteristics. On the other hand, when the temperature is lower than 400 ° C., the resin is not sufficiently carbonized, and the electrical conductivity of the positive electrode material particles cannot be increased.
[0041]
The heat treatment machine used may be either a fixed type or a rotary type, but a rotary type is preferred in order to prevent the particles from aggregating.
[0042]
For the heat treatment, a treatment of 0.5 to 4 hours is sufficient.
[0043]
DETAILED DESCRIPTION OF THE INVENTION
A typical embodiment of the present invention is as follows.
[0044]
The average particle diameter in Examples and Comparative Examples, infra and the following embodiments (D 10, D 50 and D 90) is expressed by the value measured by a laser diffraction particle size analyzer (SYMPATEC Co. RODOS) .
[0045]
The amount of carbon was indicated by a value measured using a carbon elution test.
In a 100 ml glass sample bottle, 100 ml of N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) as a solvent and 2 g each of positive electrode material particles were added, shaken 50 times by hand, and allowed to stand for 5 minutes. Let The transmittance of the supernatant was evaluated by absorption at a wavelength of 600 nm using a UV measuring device (UV-2400PC; manufactured by Shimadzu Corporation).
Permeability is 80% or more Good 60% -80% Less than 60% Impossibility When carbon is easily detached from the surface of the cathode material particles, the permeability is low, while the cathode material particles are firmly covered. For things, the permeability is high.
[0046]
The volume resistivity value was measured using a Wheatstone bridge 2768 (manufactured by Yokogawa Electric Corporation).
[0047]
The BET specific surface area was measured by a nitrogen adsorption method.
[0048]
Identification of the positive electrode material particles and analysis of the crystal structure thereof were performed by X-ray diffraction (RIGAKU, Mn-filtered Fe-Kα, 40 kV and 20 mA).
[0049]
The electrochemical characteristics of the electrode active material were evaluated by the potential sweep method. Various positive electrode material powders as a positive electrode for measurement, polytetrafluoroethylene as a binder and ketjen black as a conductive material are mixed in a 5% by weight ratio, and 0.5 g of this mixture is weighed to obtain a current collector. The working electrode was filled with a nickel mesh. A stainless steel mesh was filled with a metal lithium foil as a negative electrode. Further, lithium metal was used as a reference electrode. A solution obtained by dissolving lithium perchlorate (LiClO 4 ) at a concentration of 1 M in a solvent in which propylene carbonate and dimethoxyethane were mixed at a volume ratio of 1: 1 was used as an electrolyte.
[0050]
An electrochemical measurement cell was constructed using the above-described positive electrode for measurement, negative electrode, reference electrode, and electrolyte. Using this electrochemical cell, a charge / discharge curve was examined in a measurement range of 3.0 to 4.2 V with a current of 0.5 mA / cm 2 based on a metal lithium electrode.
[0051]
<Manufacture of active material for positive electrode>
In a Henschel mixer, 1 kg of LiCoO 2 particle powder (average particle size: 4.0 μm, volume specific resistance: 2.2 × 10 5 Ωcm, tap density: 2.42 g / ml) was charged at 960 rpm while flowing nitrogen gas at 1 l / min. Then, 8.3 g of a resol type phenol resin “Phenolite J-325” (trade name: Dainippon Ink & Chemicals, Inc.) having an OH equivalent of 185 g / equivalent and 10 g of ethanol were added.
The mixture was heated to a powder temperature of 70 ° C., stirred for about 2 hours, and then cooled to coat the surface of the LiCoO 2 particle powder with 0.49 wt% phenol resin.
[0052]
Next, the LiCoO 2 particle powder coated with the obtained phenol resin is placed in a rotary heat treatment furnace, and the product temperature is raised to 500 ° C. in 90 minutes while flowing air at a flow rate of 1 l / min. Then, carbonization of the resin was carried out by holding at 500 ° C. for 1 hour to produce LiCoO 2 particle powder coated with carbon, and then cooled to a temperature of 50 ° C. or lower to take out composite positive electrode material particle powder (A). .
[0053]
The average particle diameter of the obtained composite positive electrode material particle powder (A) is 4.2 μm when represented by D 50 , 2.0 μm when represented by D 10 , and 10.5 μm when represented by D 90 . The (D 90 / D 50 ) ratio is 2.5, the (D 50 / D 10 ) ratio is 2.1, the specific surface area is 1.0 m 2 / g, and the volume resistivity is 2 × 10 4. The Ωcm, the tap density was 2.50, the amount of carbon was 0.04%, and the carbon elution test was (good).
Furthermore, when the electric capacity of this charging / discharging was calculated | required, it was 162 mAh / g.
For comparison, the electric capacity was 157 mAh / g when the LiCoO 2 particle powder was used as it was without coating with resin.
[0054]
[Action]
In the present invention, the most important point is that when positive electrode material particles whose surfaces are coated with phenol resin or epoxy resin are heat-treated in an oxidizing atmosphere, positive electrode material particles coated with carbon can be obtained. The carbon is not easily desorbed, so that the electrical conductivity can be increased, and the electrical conductivity can be stably increased even during long-term use.
[0055]
Regarding the reason why carbon does not easily desorb from the surface of the positive electrode material particles, the present inventors coated the particle surface of the positive electrode material particles with a specific phenol resin or epoxy resin, and then heat-treated in an oxidizing atmosphere to carbonize the resin. It is considered that carbon is firmly fixed on the surface of the positive electrode material particles due to the fact that it is.
[0056]
And since the active material for positive electrodes of the secondary battery which concerns on this invention is excellent in a particle size distribution, it is the fact that it is possible to raise the filling amount to the resin of the active material for positive electrodes.
[0057]
【Example】
Next, examples and comparative examples are given.
[0058]
Example 1
In the same manner as in the embodiment of the present invention, 1 kg of LiCoO 2 particle powder (average particle diameter 1.2 μm, volume specific resistance value 3.5 × 10 5 Ωcm) is an epoxy resin “Epiclon 5300 having an epoxy equivalent of 300 g / equivalent. -70 "(trade name: manufactured by Dainippon Ink & Chemicals, Inc.) and a surface treatment with a mixed solution of 21 g and methanol 40 g. The mixture was heated to a powder temperature of 70 ° C., stirred for about 2 hours, and then cooled to obtain a particle powder in which the surface of LiCoO 2 particles was coated with an epoxy resin.
[0059]
Next, the LiCoO 2 particle powder coated with the obtained epoxy resin is put in a rotary heat treatment furnace, and the product temperature is raised to 600 ° C. in 2 hours while flowing air at a flow rate of 1 l / min. After holding at 600 ° C. for 1 hour, it was cooled to a temperature of 50 ° C. or lower and taken out.
The main production conditions at this time are shown in Table 1, and the characteristics of the obtained LiCoO 2 particle powder (B) are shown in Table 2.
[0060]
Examples 2-6, Comparative Examples 1-5
The coated cathode material particle powder coated with carbon was produced in the same manner as in the above embodiment except that the kind of cathode material particle powder, the kind and amount of resin to be coated, and the heat treatment conditions were variously changed. It was. Table 1 shows the main production conditions and Table 2 shows the characteristics.
[0061]
Comparative Example 6
300 mg LiNiO 2 particle powder (average particle size 1.5 μm, volume resistivity 4.2 × 10 5 Ωcm) and 4.5 g ketjen black “ECP-600JD” (trade name: manufactured by Lion Co., Ltd.) The treatment was performed for 30 minutes using “AM-15F” (trade name: manufactured by Hosokawa Micron Corporation).
Table 1 shows the main production conditions at this time, and Table 2 shows the characteristics of the LiNiO 2 particle powder (M) in which carbon is adhered to the obtained particle surface.
[0062]
Comparative Example 7
Novolak-type phenolic resin “Tamanol 100S” (trade name: Arakawa Chemical Industries, Ltd.) with 1 kg of LiCoO 2 particle powder (average particle size: 4.0 μm, volume resistivity: 2.2 × 10 5 Ωcm) and OH equivalent of 100 g / equivalent )) 20 g was kneaded with an extruder, and then pulverized and classified to produce composite particles. The obtained composite particle powder had an average particle size of 18.2 μm. The obtained composite particle powder is put in a rotary heat treatment furnace, and the temperature of the product is raised to 500 ° C. in 90 minutes while flowing air at a flow rate of 1 l / min, and held at 500 ° C. for 1 hour. After that, it was cooled to a temperature of 50 ° C. or lower and taken out.
[0063]
Table 2 shows the characteristics of the LiCoO 2 particle powder (N) whose surface is coated with carbon.
[0064]
[Table 1]
[Table 2]
【The invention's effect】
Since the active material for positive electrode of the secondary battery according to the present invention is coated with carbon firmly on the particle surface of the positive electrode material particle, it is not easily detached from the particle surface even by stress when adjusting the positive electrode. Since the conductivity is excellent and the filling property and dispersibility in the resin are excellent, it is suitable as an active material for a positive electrode of a secondary battery.
[0067]
When the positive electrode active material is used, the charge / discharge capacity of the secondary battery can be increased.
Claims (4)
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| EP1936721B1 (en) | 2005-09-21 | 2015-11-11 | Kanto Denka Kogyo Co., Ltd. | Positive electrode active material, method for producing same, and nonaqueous electrolyte battery having positive electrode containing positive electrode active material |
| JP5180448B2 (en) * | 2006-08-09 | 2013-04-10 | 関東電化工業株式会社 | Spinel type lithium manganate and method for producing the same, and positive electrode active material and nonaqueous electrolyte battery using spinel type lithium manganate |
| JP5352069B2 (en) * | 2007-08-08 | 2013-11-27 | トヨタ自動車株式会社 | Positive electrode material, positive electrode plate, secondary battery, and method for manufacturing positive electrode material |
| JP5464330B2 (en) * | 2009-07-31 | 2014-04-09 | 戸田工業株式会社 | Cathode active material for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery |
| JP6077205B2 (en) * | 2011-09-22 | 2017-02-08 | 住友大阪セメント株式会社 | Electrode material and manufacturing method thereof |
| JP5861992B2 (en) * | 2011-11-09 | 2016-02-16 | 株式会社Ｇｓユアサ | Non-aqueous electrolyte secondary battery active material, method for producing the active material, non-aqueous electrolyte secondary battery electrode, and non-aqueous electrolyte secondary battery |
| JP5594309B2 (en) * | 2012-03-27 | 2014-09-24 | Ｔｄｋ株式会社 | Positive electrode material for lithium ion secondary battery, positive electrode for lithium ion secondary battery and lithium ion secondary battery |
| DE112013006722B4 (en) * | 2013-02-22 | 2020-10-15 | Kabushiki Kaisha Toyota Jidoshokki | Negative electrode active material, manufacturing method for the same and electric storage apparatus |
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