JP5000811B2 - Lithium titanate powder and its use - Google Patents
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- JP5000811B2 JP5000811B2 JP2001131054A JP2001131054A JP5000811B2 JP 5000811 B2 JP5000811 B2 JP 5000811B2 JP 2001131054 A JP2001131054 A JP 2001131054A JP 2001131054 A JP2001131054 A JP 2001131054A JP 5000811 B2 JP5000811 B2 JP 5000811B2
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Description
【０００１】
【発明の属する技術分野】
本発明は、リチウム二次電池の活物質として有用なチタン酸リチウム粉体及びそれを用いたリチウム二次電池に関するものである。
【０００２】
【従来の技術】
リチウム二次電池は、そのエネルギー密度の高さから携帯電話やノートパソコン用の電源として進歩してきたが、近年のＩＴ技術の進歩により携帯端末機器の小型、軽量化に伴って、その電源である電池にも更に小型、高容量化が求められるようになってきた。
【０００３】
リチウムチタン複合酸化物であるチタン酸リチウムは、代表的なものにＬｉ4Ｔｉ5Ｏ12があり、リチウム二次電池の活物質とした場合、リチウム基準で１．５Ｖの電圧を有し、サイクル劣化が小さく長寿命であることが特徴である。また、時計用小型リチウム二次電池の活物質として実績を持ち、充放電に際して膨張・収縮が無視できるという特徴から大型電池用の活物質としても注目されている。この材料は正極活物質としての利用の他、負極活物質としての利用面も開けており、その将来が期待されるものである。
【０００４】
電池の小型、高容量化のためには活物質自体の電気容量を大きくする方法があり、例えばＷＯ９９／０３７８４にはチタン酸リチウムの一部をプロトンで置換して水素化することにより、理論容量を上回る充放電容量が得られることが提案されている。しかしながら活物質の充填密度を向上させて電気容量を大きくする方法については未だに報告がなされていない。
【０００５】
【発明が解決しようとする課題】
本発明は、チタン酸リチウムを用いるリチウム二次電池特性を改良する為に、ポリオール及び／又はカップリング剤で表面被覆されたチタン酸リチウム粉体を製造すること、及び該チタン酸リチウム粉体を用いたリチウム二次電池を提供することにある。
【０００６】
【課題を解決するための手段】
本発明者らは上記目的を達成すべく鋭意研究を重ねた結果、ポリオール及び／又はカップリング剤で表面被覆したチタン酸リチウム粉体はタップ密度が向上し、電極合剤を混練したときの塗料粘度を低減させることができると判った。また、このチタン酸リチウムの粉体を活物質として使用したリチウム二次電池は、優れた充放電特性を示すことを見出し、本発明を完成させた。
【０００７】
すなわち、本発明のチタン酸リチウム粉体は、Ｌｉ4Ｔｉ5Ｏ12を主成分とする粉体であって、該粉体の表面が、ポリオール及び／又はカップリング剤で被覆されていることを特徴とする。
【０００８】
また、本発明のチタン酸リチウムにおいて、その粉体のタップ密度が０．７５ｇ／ｍｌ以上であっても良い。
【０００９】
また、前記チタン酸リチウム粉体を正極又は負極活物質として用いた電池用電極を提供することができる。
【００１０】
また、前記電池用電極を用いたリチウム二次電池を提供することができる。
【００１１】
更に、前記チタン酸リチウム粉体を正極活物質とし、金属Ｌｉを負極とするリチウム二次電池であって、充・放電電圧が１．４〜１．６Ｖ、初期放電容量が１５０ｍＡｈ／ｇ以上であるリチウム二次電池を提供することができる。
【００１２】
【発明の実施の形態】
本発明のチタン酸リチウム粉体は、各粒子がポリオール及び／又はカップリング剤で表面被覆され、Ｌｉ4Ｔｉ5Ｏ12を主成分とすることを特徴とし、好ましくは、タップ密度が０．７５ｇ／ｍｌ以上である。このタップ密度の範囲内で、後述する優れた充放電特性を示すリチウム二次電池用の電極活物質を調製することができる。
【００１３】
表面被覆する前の基体となるチタン酸リチウム粉体は、代表的には原料を水中で均一に混合する工程、該混合物を乾燥する工程及び熱処理する工程により製造できる。
【００１４】
まず、リチウム原料として水酸化リチウム、水酸化リチウム・一水和物、酸化リチウム、炭酸水素リチウム、炭酸リチウム等を水に混合又は溶解する。この液にＬｉとＴｉの原子比が４：５となるように酸化チタンを混合する。使用する酸化チタンはアナターゼ型二酸化チタン又は含水酸化チタンが好ましい。アナターゼ型二酸化チタンについては、純度が少なくとも９５％以上が必要であり、好ましくは９８％以上のものである。純度が９５％未満の場合、単位活物質当たりの容量が下がってしまうため好ましくない。含水酸化チタンについては、焼成してアナターゼ型二酸化チタンとしたときに上記範囲の純度となるものであり、この場合、焼成前における含水酸化チタンの純度の目安は９０％以上である。
【００１５】
前記の原子比の条件を満たすと共に、混合液のスラリー濃度は、Ｌｉ原料が０．４８〜４．８モル／Ｌ、酸化チタンが０．６０〜６．００モル／Ｌであることが好ましい。これらの範囲より濃度が高いと均一混合に強い撹拌力が必要となり、また乾燥時における配管閉塞等のトラブルの原因となり好ましくない。前記の範囲より濃度が低いと蒸発水分量が増加し、乾燥コストが上がるので好ましくない。乾燥方法はそのまま乾燥しても良いし、噴霧乾燥、流動層乾燥、転動造粒乾燥あるいは凍結乾燥を単独又は組み合わせて使用しても良い。
【００１６】
得られた乾燥物を大気中で熱処理し、平均粒径が０．１〜５０μｍであるチタン酸リチウム粒子を得る。熱処理条件は、７００〜１０００℃で１〜１０時間、好ましくは８００〜９００℃で５〜１０時間である。７００℃未満では酸化チタンとリチウム化合物の反応が不十分となり、１０００℃を超えた場合、チタン酸リチウムの焼結が顕著に起こり、電池特性が悪くなるので好ましくない。
【００１７】
前記のようにして造粒したチタン酸リチウムに対して、ポリオール及び／又はカップリング剤による表面被覆処理を行う。
【００１８】
ポリオールの種類は特に限定されないが、ペンタエリトリトール、トリエチロールエタン、トリメチロールプロパン等を単独又は組み合わせて使用できる。処理方法は前記ポリオールを可溶な溶媒に溶解後、その溶液と前記粒状チタン酸リチウムとを混合する。ポリオールの添加量は、基体となるチタン酸リチウムに対して０．２〜２．０質量％、好ましくは０．５〜１．５質量％である。添加量が０．２質量％より少ないと十分なタップ密度の向上が得られず、また塗料粘度の低減効果も少ないので好ましくない。また、２．０質量％より多いと放電容量の低下をもたらし好ましくない。
【００１９】
混合後は５０〜２００℃、好ましくは８０〜１５０℃で熱処理を行う。熱処理時間は、３０分〜２４時間、好ましくは１〜１０時間である。これによりチタン酸リチウムの各粒子表面の水酸基とポリオール中の水酸基とが反応し、チタン酸リチウム粒子表面に有機層が形成される。ポリオール由来の有機層が形成されたチタン酸リチウム粉体は、被覆有機層の有機官能基により粒子間の相互作用が減少し、タップ密度を向上させることが可能となる。前記熱処理温度が５０℃より低いと有機層形成の反応が進行せず、また２００℃より高いとポリオールが分解し所望の有機層が形成されず、タップ密度向上の効果が得られないので好ましくない。
【００２０】
また、前記基体となるチタン酸リチウムの焼結に対して粉砕処理が必要である場合は、その粉砕前にポリオールは溶解せずに固体のまま添加することができ、粉砕処理がポリオールの融解及び被覆を兼ねる。この方式によれば、粉砕効率の向上、粉砕時の凝結や塊状化を抑制する効果がある。
【００２１】
カップリング剤の種類は特に限定されないが、シランカップリング剤、チタンカップリング剤、アルミニウムカップリング剤等が使用でき、中でもシランカップリング剤が好ましい。シランカップリング剤としては、例えばビニルトリクロルシラン、ビニルトリスシラン、ビニルトリエトキシシラン、ビニルトリメトキシシラン、γ−メタクリロキシプロピルトリメトキシシラン、γ−グリシドキシプロピルトリメトキシシラン、γ−アミノプロピルトリエトキシシラン、γ−メルカプトプロピルトリメトキシシラン、γ−クロロプロピルトリメトキシシラン等を単独又は組み合わせて使用できる。処理方法は前記カップリング剤を前記チタン酸リチウムと混合する。カップリング剤の添加量は基体となるチタン酸リチウムに対して、０．２〜２．０質量％、好ましくは０．５〜１．５質量％である。添加量が０．２質量％より少ないと十分なタップ密度の向上が得られず、また塗料粘度の低減効果も少ないので好ましくない。また２．０質量％より多いと放電容量の低下をもたらし好ましくない。
【００２２】
混合後は、５０〜２００℃、好ましくは８０〜１５０℃で熱処理を行う。熱処理時間は３０分〜２４時間、好ましくは１〜１０時間である。これによりチタン酸リチウム粒子表面の水酸基とカップリング剤の官能基とが反応し、粒子表面にカップリング剤が被覆される。この結果、チタン酸リチウム粉体における粒子間の相互作用が減少しタップ密度を上げることができる。前記熱処理温度が５０℃より低いと未反応のカップリング剤が残存し十分な効果が得られず、また２００℃より高いとカップリング剤が分解するので好ましくない。
【００２３】
また、前記ポリオールと前記カップリング剤を適宜組み合わせて使用することもできる。
【００２４】
本発明の表面被覆処理されたチタン酸リチウム粉体は、電極作製時に一般的に用いられるｎ−メチル−２−ピロリドン中への分散性が向上し、塗料粘度を低減させることができる。塗料粘度が下がる結果、高濃度で塗料の作製が可能となる為、集電体上への充填密度が向上する。
【００２５】
上記のように合成したチタン酸リチウム粉体を正極活物質として使用し、負極にＬｉ金属を使用したリチウム二次電池としてコイン型二次電池を作製し、充・放電試験を行った。その結果、本発明のチタン酸リチウム粉体を用いた場合には、充放電での電圧が１．４〜１．６Ｖを満足し、初期放電容量が１５０ｍＡｈ／ｇ以上と高い値を得ることができた。また放電レート３．０Ｃの容量は１１０ｍＡｈ／ｇ以上であり、無処理の場合の１０５ｍＡｈ／ｇに比べて大きいことが見出された。
【００２６】
【実施例】
以下、実施例及び比較例を基に具体的に説明するが、本発明はこれらの実施例に限定されるものではない。
【００２７】
【実施例１】
水酸化リチウム（ＬｉＯＨ・Ｈ2Ｏ）を１２％濃度で水に溶解し、該溶解液にアナターゼ型二酸化チタンをＬｉとＴｉの原子比が４：５となる量を添加し混合した。混合物を１１０℃で噴霧乾燥し、８７５℃で６時間熱処理を行いチタン酸リチウムを作製した。このチタン酸リチウムにトリメチロールプロパンのエタノール溶液を添加し、１１０℃で１．５時間の熱処理を行い粉体試料を作製した。トリメチロールプロパンの添加量は１．０質量％とした。本試料のタップ密度をＪＩＳ−Ｋ−５１０１タップ法により測定した。また本試料８２重量部とアセチレンブラック９重量部及びポリフッ化ビニリデン９重量部とを混合後、N−メチル−２−ピロリドンに固形分濃度４６．５％でハイシェアーミキサーにより５分間混練し、塗料を作製した。この塗料の粘度をＢ型粘度計により測定した。
【００２８】
次に上記塗料をアルミ箔上にドクターブレード法で乾燥後の厚みが０．０１ｇ／ｃｍ2になるように塗布した。１１０℃で真空乾燥後、初期電極合剤の厚みに対して８０％にロールプレスした。１ｃｍ2に打ち抜き後、図１に示すコイン電池の正極３とした。図１において負極４は金属リチウム板を、電解液はエチレンカーボネートとジメチルカーボネートの等容量混合物にＬｉＰＦ6を１ｍｏｌ／Ｌで溶解したものを、セパレーター５はポリプロピレン多孔膜を使用した。上記により作製したコイン電池を用いて電流密度０．２ｍＡ／ｃｍ2で１．０Ｖまで放電後、同電流密度で３．０Ｖまで充電し、このサイクルを３回繰り返した。その後、放電レートが３．０Ｃとなる電流密度で放電を行った。表１にタップ密度、塗料粘度及び放電容量の測定結果を示す。
【００２９】
【実施例２】
チタン酸リチウムにビニルトリエトキシシランを０．５質量％混合した以外は実施例１と同様に行い、タップ密度、塗料粘度及び放電容量を測定した。結果を表１に示す。
【００３０】
【実施例３】
チタン酸リチウムにビニルトリエトキシシランを１．０質量％混合した以外は実施例１と同様に行い、タップ密度、塗料粘度及び放電容量を測定した。結果を表１に示す。
【００３１】
【実施例４】
チタン酸リチウムにビニルトリエトキシシランを１．５質量％混合した以外は実施例１と同様に行い、タップ密度、塗料粘度及び放電容量を測定した。結果を表１に示す。
【００３２】
【実施例５】
チタン酸リチウムにビニルトリエトキシシランを２．０質量％混合した以外は実施例１と同様に行い、タップ密度、塗料粘度及び放電容量を測定した。結果を表１に示す。
【００３３】
【実施例６】
チタン酸リチウムにγ−メタクリロキシプロピルトリメトキシシランを１．５質量％混合した以外は実施例１と同様に行い、タップ密度、塗料粘度及び放電容量を測定した。結果を表１に示す。
【００３４】
【実施例７】
チタン酸リチウムにγ−アミノプロピルトリエトキシシランを１．５質量％混合した以外は実施例１と同様に行い、タップ密度、塗料粘度及び放電容量を測定した。結果を表１に示す。
【００３５】
【比較例１】
チタン酸リチウムにポリオール又はカップリング剤のいずれも混合しなかった以外は実施例１と同様に行い、タップ密度、塗料粘度及び放電容量を測定した。結果を表１に示す。
【００３６】
表１に示されるように実施例１〜４は比較例１に対してタップ密度が向上し塗料粘度も低下している。また実施例１〜３はローレート（０．１５Ｃ）放電容量を維持しながら、ハイレート（３．０Ｃ）放電容量を向上させることができた。
【００３７】
【表１】
【発明の効果】
以上説明したように、本発明のチタン酸リチウム粉体は、その粉体表面がポリオール及び／又はカップリング剤で被覆されているので、被覆しないものに比べタップ密度の向上、塗料粘度の低下及びハイレートの放電特性を向上させることができる。
【図面の簡単な説明】
【図１】本発明の実施例及び比較例のチタン酸リチウム粉体を正極に使用したコイン電池の断面図である。
【符号の説明】
正極 ３
負極 ４[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lithium titanate powder useful as an active material for a lithium secondary battery and a lithium secondary battery using the same.
[0002]
[Prior art]
Lithium secondary batteries have made progress as power sources for mobile phones and notebook PCs due to their high energy density. However, with the recent advances in IT technology, the power source has become smaller and lighter. Batteries are also required to be smaller and have higher capacity.
[0003]
Lithium titanate which is a lithium-titanium composite oxide is typically Li 4 Ti 5 O 12 , and has a voltage of 1.5 V based on lithium when used as an active material for a lithium secondary battery. It is characterized by small deterioration and long life. In addition, it has a track record as an active material for small lithium secondary batteries for watches, and has attracted attention as an active material for large batteries due to the feature that expansion and contraction can be ignored during charging and discharging. In addition to being used as a positive electrode active material, this material is also open to use as a negative electrode active material, and its future is expected.
[0004]
In order to reduce the size and increase the capacity of the battery, there is a method of increasing the electric capacity of the active material itself. For example, WO99 / 03784 has a theoretical capacity by substituting a part of lithium titanate with a proton and hydrogenating it. It has been proposed that a charge / discharge capacity greater than 1 can be obtained. However, no report has yet been made on a method for increasing the electric capacity by increasing the packing density of the active material.
[0005]
[Problems to be solved by the invention]
The present invention provides a lithium titanate powder whose surface is coated with a polyol and / or a coupling agent in order to improve the characteristics of a lithium secondary battery using lithium titanate, and the lithium titanate powder It is in providing the used lithium secondary battery.
[0006]
[Means for Solving the Problems]
As a result of intensive research to achieve the above object, the inventors of the present invention have improved the tap density of the lithium titanate powder surface-coated with a polyol and / or a coupling agent, and the paint when the electrode mixture is kneaded. It has been found that the viscosity can be reduced. Further, the present inventors have found that a lithium secondary battery using the lithium titanate powder as an active material exhibits excellent charge / discharge characteristics and completed the present invention.
[0007]
That is, the lithium titanate powder of the present invention is a powder mainly composed of Li 4 Ti 5 O 12 , and the surface of the powder is coated with a polyol and / or a coupling agent. Features.
[0008]
Moreover, in the lithium titanate of the present invention, the tap density of the powder may be 0.75 g / ml or more.
[0009]
Moreover, the battery electrode using the said lithium titanate powder as a positive electrode or a negative electrode active material can be provided.
[0010]
Moreover, the lithium secondary battery using the said battery electrode can be provided.
[0011]
Furthermore, a lithium secondary battery using the lithium titanate powder as a positive electrode active material and a metal Li as a negative electrode with a charge / discharge voltage of 1.4 to 1.6 V and an initial discharge capacity of 150 mAh / g or more. A lithium secondary battery can be provided.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The lithium titanate powder of the present invention is characterized in that each particle is surface-coated with a polyol and / or a coupling agent, and is mainly composed of Li 4 Ti 5 O 12. Preferably, the tap density is 0.75 g. / Ml or more. Within this tap density range, an electrode active material for a lithium secondary battery exhibiting excellent charge / discharge characteristics described later can be prepared.
[0013]
The lithium titanate powder as a base before surface coating can be typically produced by a step of uniformly mixing raw materials in water, a step of drying the mixture, and a step of heat treatment.
[0014]
First, lithium hydroxide, lithium hydroxide monohydrate, lithium oxide, lithium hydrogen carbonate, lithium carbonate or the like is mixed or dissolved in water as a lithium raw material. Titanium oxide is mixed with this liquid so that the atomic ratio of Li and Ti is 4: 5. The titanium oxide used is preferably anatase type titanium dioxide or hydrous titanium oxide. The anatase-type titanium dioxide needs to have a purity of at least 95%, preferably 98% or more. When the purity is less than 95%, the capacity per unit active material decreases, which is not preferable. The hydrous titanium oxide has a purity in the above range when calcined to obtain anatase type titanium dioxide. In this case, the standard of the hydrous titanium oxide purity before firing is 90% or more.
[0015]
While satisfy | filling the said atomic ratio, it is preferable that the slurry density | concentrations of a liquid mixture are 0.48-4.8 mol / L of Li raw materials, and 0.60-6.00 mol / L of titanium oxide. If the concentration is higher than these ranges, a strong stirring force is required for uniform mixing, and troubles such as piping clogging during drying are undesirable. If the concentration is lower than the above range, the amount of evaporated water increases and the drying cost increases, which is not preferable. As the drying method, it may be dried as it is, or spray drying, fluidized bed drying, rolling granulation drying or freeze drying may be used alone or in combination.
[0016]
The obtained dried product is heat-treated in the atmosphere to obtain lithium titanate particles having an average particle size of 0.1 to 50 μm. The heat treatment conditions are 700 to 1000 ° C. for 1 to 10 hours, preferably 800 to 900 ° C. for 5 to 10 hours. When the temperature is lower than 700 ° C., the reaction between titanium oxide and the lithium compound becomes insufficient, and when the temperature exceeds 1000 ° C., lithium titanate is significantly sintered and battery characteristics are deteriorated.
[0017]
The lithium titanate granulated as described above is subjected to a surface coating treatment with a polyol and / or a coupling agent.
[0018]
Although the kind of polyol is not particularly limited, pentaerythritol, triethylolethane, trimethylolpropane and the like can be used alone or in combination. In the treatment method, the polyol is dissolved in a soluble solvent, and then the solution and the granular lithium titanate are mixed. The addition amount of the polyol is 0.2 to 2.0% by mass, preferably 0.5 to 1.5% by mass with respect to lithium titanate serving as the base. If the addition amount is less than 0.2% by mass, a sufficient tap density improvement cannot be obtained, and the effect of reducing the viscosity of the paint is small, which is not preferable. On the other hand, if it is more than 2.0% by mass, the discharge capacity is lowered, which is not preferable.
[0019]
After mixing, heat treatment is performed at 50 to 200 ° C., preferably 80 to 150 ° C. The heat treatment time is 30 minutes to 24 hours, preferably 1 to 10 hours. Thereby, the hydroxyl group on the surface of each particle of lithium titanate reacts with the hydroxyl group in the polyol to form an organic layer on the surface of the lithium titanate particle. In the lithium titanate powder in which the polyol-derived organic layer is formed, the interaction between particles is reduced by the organic functional group of the coated organic layer, and the tap density can be improved. If the heat treatment temperature is lower than 50 ° C., the reaction for forming the organic layer does not proceed, and if it is higher than 200 ° C., the polyol is decomposed and the desired organic layer is not formed, and the effect of improving the tap density is not preferable. .
[0020]
In addition, when a pulverization process is required for the sintering of the lithium titanate serving as the substrate, the polyol can be added as a solid without being dissolved before the pulverization. Also serves as a coating. According to this method, there is an effect of improving the pulverization efficiency and suppressing condensation and agglomeration during pulverization.
[0021]
Although the kind of coupling agent is not specifically limited, A silane coupling agent, a titanium coupling agent, an aluminum coupling agent, etc. can be used, and a silane coupling agent is especially preferable. Examples of the silane coupling agent include vinyltrichlorosilane, vinyltrissilane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-aminopropyltri Ethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane and the like can be used alone or in combination. In the treatment method, the coupling agent is mixed with the lithium titanate. The addition amount of the coupling agent is 0.2 to 2.0% by mass, preferably 0.5 to 1.5% by mass with respect to the lithium titanate serving as the base. If the addition amount is less than 0.2% by mass, a sufficient tap density improvement cannot be obtained, and the effect of reducing the viscosity of the paint is small, which is not preferable. On the other hand, if it is more than 2.0% by mass, the discharge capacity is lowered, which is not preferable.
[0022]
After mixing, heat treatment is performed at 50 to 200 ° C, preferably 80 to 150 ° C. The heat treatment time is 30 minutes to 24 hours, preferably 1 to 10 hours. As a result, the hydroxyl group on the surface of the lithium titanate particle reacts with the functional group of the coupling agent, and the particle surface is coated with the coupling agent. As a result, the interaction between particles in the lithium titanate powder can be reduced and the tap density can be increased. If the heat treatment temperature is lower than 50 ° C, an unreacted coupling agent remains and a sufficient effect cannot be obtained, and if it is higher than 200 ° C, the coupling agent is decomposed, which is not preferable.
[0023]
Moreover, the said polyol and the said coupling agent can also be used in combination as appropriate.
[0024]
The surface-coated lithium titanate powder of the present invention has improved dispersibility in n-methyl-2-pyrrolidone that is generally used during electrode production, and can reduce paint viscosity. As a result of the lowering of the viscosity of the paint, it becomes possible to produce the paint at a high concentration, so that the packing density on the current collector is improved.
[0025]
A coin-type secondary battery was produced as a lithium secondary battery using the lithium titanate powder synthesized as described above as the positive electrode active material and Li metal as the negative electrode, and a charge / discharge test was performed. As a result, when the lithium titanate powder of the present invention is used, the charge / discharge voltage satisfies 1.4 to 1.6 V, and the initial discharge capacity is as high as 150 mAh / g or higher. did it. Moreover, the capacity | capacitance of the discharge rate 3.0C was 110 mAh / g or more, and it was found that it was large compared with 105 mAh / g in the case of no process.
[0026]
【Example】
Hereinafter, although concretely demonstrated based on an Example and a comparative example, this invention is not limited to these Examples.
[0027]
[Example 1]
Lithium hydroxide (LiOH.H 2 O) was dissolved in water at a concentration of 12%, and an anatase-type titanium dioxide was added to the solution in an amount such that the atomic ratio of Li and Ti was 4: 5. The mixture was spray-dried at 110 ° C. and heat-treated at 875 ° C. for 6 hours to produce lithium titanate. An ethanol solution of trimethylolpropane was added to this lithium titanate, followed by heat treatment at 110 ° C. for 1.5 hours to prepare a powder sample. The amount of trimethylolpropane added was 1.0% by mass. The tap density of this sample was measured by the JIS-K-5101 tap method. Also, 82 parts by weight of this sample, 9 parts by weight of acetylene black and 9 parts by weight of polyvinylidene fluoride were mixed and then kneaded with N-methyl-2-pyrrolidone at a solid content concentration of 46.5% for 5 minutes using a high shear mixer. Was made. The viscosity of this paint was measured with a B-type viscometer.
[0028]
Next, the paint was applied onto an aluminum foil by a doctor blade method so that the thickness after drying was 0.01 g / cm 2 . After vacuum drying at 110 ° C., roll pressing was performed to 80% with respect to the thickness of the initial electrode mixture. After punching out to 1 cm 2 , the positive electrode 3 of the coin battery shown in FIG. 1 was obtained. In FIG. 1, the
[0029]
[Example 2]
The tap density, paint viscosity, and discharge capacity were measured in the same manner as in Example 1 except that 0.5% by mass of vinyl triethoxysilane was mixed with lithium titanate. The results are shown in Table 1.
[0030]
[Example 3]
The tap density, coating viscosity, and discharge capacity were measured in the same manner as in Example 1 except that 1.0% by mass of vinyl triethoxysilane was mixed with lithium titanate. The results are shown in Table 1.
[0031]
[Example 4]
The tap density, paint viscosity, and discharge capacity were measured in the same manner as in Example 1 except that 1.5% by mass of vinyltriethoxysilane was mixed with lithium titanate. The results are shown in Table 1.
[0032]
[Example 5]
The tap density, paint viscosity, and discharge capacity were measured in the same manner as in Example 1 except that 2.0% by mass of vinyl triethoxysilane was mixed with lithium titanate. The results are shown in Table 1.
[0033]
[Example 6]
The tap density, paint viscosity, and discharge capacity were measured in the same manner as in Example 1 except that 1.5% by mass of γ-methacryloxypropyltrimethoxysilane was mixed with lithium titanate. The results are shown in Table 1.
[0034]
[Example 7]
The tap density, paint viscosity, and discharge capacity were measured in the same manner as in Example 1 except that 1.5% by mass of γ-aminopropyltriethoxysilane was mixed with lithium titanate. The results are shown in Table 1.
[0035]
[Comparative Example 1]
The tap density, paint viscosity, and discharge capacity were measured in the same manner as in Example 1 except that neither lithium nor a coupling agent was mixed with lithium titanate. The results are shown in Table 1.
[0036]
As shown in Table 1, in Examples 1 to 4, the tap density was improved and the paint viscosity was also reduced as compared with Comparative Example 1. In Examples 1 to 3, the high rate (3.0 C) discharge capacity could be improved while maintaining the low rate (0.15 C) discharge capacity.
[0037]
[Table 1]
【Effect of the invention】
As described above, since the lithium titanate powder of the present invention has a powder surface coated with a polyol and / or a coupling agent, the tap density is improved, the paint viscosity is reduced, and the powder is not coated. High rate discharge characteristics can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a coin battery using lithium titanate powders of Examples and Comparative Examples of the present invention as a positive electrode.
[Explanation of symbols]
Positive electrode 3
Claims (3)
前記混合水溶液を乾燥させて乾燥物を得る工程、
前記乾燥物を大気中で熱処理してチタン酸リチウム粉体を得る工程、
ポリオールの溶液及び／又はシランカップリング剤と前記チタン酸リチウム粉体とを混合する工程、及び
前記混合物を熱処理してチタン酸リチウム粉体を前記ポリオール及び／又はシランカップリング剤で被覆する工程、
を含む、Ｌｉ ４ Ｔｉ ５ Ｏ １２ を主成分とする、液体電解質を使用するリチウム二次電池において正極又は負極の活物質として用いるチタン酸リチウム粉体を製造する方法。A step of uniformly mixing raw materials of lithium titanate powder in water;
Drying the mixed aqueous solution to obtain a dried product;
A step of heat-treating the dried product in the air to obtain a lithium titanate powder;
A step of mixing a solution of a polyol and / or a silane coupling agent and the lithium titanate powder, and a step of heat-treating the mixture to coat the lithium titanate powder with the polyol and / or silane coupling agent,
A lithium titanate powder used as an active material for a positive electrode or a negative electrode in a lithium secondary battery using a liquid electrolyte , the main component of which is Li 4 Ti 5 O 12 .
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| WO2003008334A1 (en) * | 2001-07-20 | 2003-01-30 | Altair Nanomaterials Inc. | Process for making lithium titanate |
| JP4237074B2 (en) * | 2004-02-16 | 2009-03-11 | ソニー株式会社 | Cathode active material for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery |
| JP4941623B2 (en) * | 2004-07-28 | 2012-05-30 | 株式会社Ｇｓユアサ | Electrode material for electrochemical device, method for producing the same, electrode for electrochemical device, and electrochemical device |
| JP5083743B2 (en) * | 2005-07-06 | 2012-11-28 | 株式会社 東北テクノアーチ | Lithium battery |
| CN1305166C (en) * | 2005-07-28 | 2007-03-14 | 黑龙江中强能源科技有限公司 | Nano-lithium ion cell and mfg. method thereof |
| JP4826199B2 (en) * | 2005-10-14 | 2011-11-30 | 株式会社豊田中央研究所 | Water-based lithium secondary battery |
| KR100749486B1 (en) | 2005-10-31 | 2007-08-14 | 삼성에스디아이 주식회사 | Negative active material for rechargeable lithium battery, method of preparing same and rechargeable lithium battery comprising same |
| KR100778450B1 (en) | 2006-11-22 | 2007-11-28 | 삼성에스디아이 주식회사 | Negative active material for rechargeable lithium battery, method of preparing same, and rechargeable lithium battery comprising same |
| KR100814880B1 (en) | 2006-11-22 | 2008-03-18 | 삼성에스디아이 주식회사 | Negative active material for rechargeable lithium battery, method of preparing thereof, and rechargeable lithium battery comprising the same |
| JP2010177030A (en) * | 2009-01-29 | 2010-08-12 | Nippon Chem Ind Co Ltd | Surface treating agent of lithium based composite oxide, surface treating liquid of lithium based composite oxide, electrolyte for lithium-ion secondary battery, positive electrode active material for surface-treated lithium-ion secondary battery and method of manufacturing the same, negative electrode active material for surface-treated lithium-ion secondary battery and method of manufacturing the same, and lithium-ion secondary battery and method of manufacturing the same |
| CA2769178A1 (en) * | 2009-07-31 | 2011-02-03 | Toda Kogyo Corporation | Positive electrode active substance for non-aqueous electrolyte secondary batteries, and non-aqueous electrolyte secondary battery |
| KR101134474B1 (en) | 2009-12-03 | 2012-04-13 | 전남대학교산학협력단 | Anode material with high rate-capability and high Capacity for Lithium secondary battery and Process for synthesizing the same |
| JP5717461B2 (en) | 2011-02-17 | 2015-05-13 | 株式会社東芝 | Battery electrode and method for manufacturing the same, non-aqueous electrolyte battery, battery pack and active material |
| CN102800862A (en) * | 2012-07-30 | 2012-11-28 | 彩虹集团公司 | Titanium composite material, preparation method thereof and method for preparing cathode using composite material |
| KR101481546B1 (en) | 2012-12-21 | 2015-01-13 | 주식회사 코캄 | Electrode active material composite, electrode and lithium secondary battery comprising the same |
| KR20160063332A (en) * | 2013-09-30 | 2016-06-03 | 도판 인사츠 가부시키가이샤 | Electrode for secondary batteries, and secondary battery |
| JP5790745B2 (en) * | 2013-11-28 | 2015-10-07 | 住友大阪セメント株式会社 | ELECTRODE MATERIAL FOR LITHIUM ION SECONDARY BATTERY AND METHOD FOR PRODUCING THE SAME |
| WO2015166620A1 (en) * | 2014-05-02 | 2015-11-05 | ソニー株式会社 | Battery, battery pack, battery module, electronic device, electric vehicle, electricity storage device and electric power system |
| CN106450262B (en) * | 2016-10-28 | 2019-04-16 | 上海纳米技术及应用国家工程研究中心有限公司 | A kind of hollow sphere pattern lithium titanate anode material and preparation method and application |
| JP6833752B2 (en) | 2018-03-23 | 2021-02-24 | 株式会社東芝 | Rechargeable batteries, battery packs, vehicles and stationary power supplies |
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| JPH04272668A (en) * | 1991-02-27 | 1992-09-29 | Sony Corp | Organic electrolyte secondary battery |
| JP2000156245A (en) * | 1998-11-19 | 2000-06-06 | Japan Storage Battery Co Ltd | Nonaqueous electrolyte battery |
| JP2000223147A (en) * | 1999-02-02 | 2000-08-11 | Matsushita Electric Ind Co Ltd | Alkaline storage battery |
| JP2000311708A (en) * | 1999-04-27 | 2000-11-07 | Kyocera Corp | Manufacture of battery formed entirely of solid lithium |
| JP4228163B2 (en) * | 1999-05-14 | 2009-02-25 | 住友金属鉱山株式会社 | Cathode active material for non-aqueous electrolyte secondary battery and method for producing the same |
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