JP2017043496A - Lithium transition metal complex oxide and method of producing the same - Google Patents

Lithium transition metal complex oxide and method of producing the same Download PDF

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JP2017043496A
JP2017043496A JP2015164555A JP2015164555A JP2017043496A JP 2017043496 A JP2017043496 A JP 2017043496A JP 2015164555 A JP2015164555 A JP 2015164555A JP 2015164555 A JP2015164555 A JP 2015164555A JP 2017043496 A JP2017043496 A JP 2017043496A
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transition metal
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瞬 岩田
Shun Iwata
瞬 岩田
泉　武志
Takeshi Izumi
武志 泉
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Shin Nihon Denko Co Ltd
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    • 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
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Abstract

PROBLEM TO BE SOLVED: To provide: a lithium transition metal complex oxide as a secondary battery cathode active material that inhibits resistance increase accompanying a high-temperature cycle of a secondary battery and exhibits little reduction of discharge capacity and discharge voltage; and a method of producing the same.SOLUTION: A lithium transition metal complex oxide used a cathode active material comprises complex particles with the maximum particle size of 50 μm or less in which zirconium oxide having a specific surface area of 30-90 m/g in an amount of 0.1 to 1.0 mass% is attached to surfaces of particles of a lithium transition metal complex oxide having a chemical composition represented by general formula LiNiCoMnMO, where M is one or more metal elements selected from Al, Mg, W and Zr, and x, y, z and w are in the respective ranges -0.05≤x≤0.05, 0.3≤y<0.9, 0.05≤z≤0.35, and 0≤w≤0.1.SELECTED DRAWING: Figure 1

Description

本発明は、二次電池用正極活物質として、高温サイクルにともなう抵抗上昇を抑え、放電容量及び放電電圧の低下が小さい、リチウム遷移金属複合酸化物及びその製造方法に関する。   The present invention relates to a lithium transition metal composite oxide and a method for producing the same as a positive electrode active material for a secondary battery, which suppresses an increase in resistance caused by a high temperature cycle and has a small decrease in discharge capacity and discharge voltage.

リチウムイオン二次電池は起電力やエネルギー密度の点で優れており、小型ビデオカメラ、携帯電話、ノートパソコンなどの携帯電子・通信機器用の電池として広く使用されている。近年では携帯用の電子機器のみならず自動車用、蓄電設備などの移動体・大型向け電源としても注目されてきており、これらの分野向けの開発も活発に進められてきている。   Lithium ion secondary batteries are excellent in terms of electromotive force and energy density, and are widely used as batteries for portable electronic and communication devices such as small video cameras, mobile phones, and notebook computers. In recent years, attention has been paid not only to portable electronic devices but also to power sources for mobiles and large-size vehicles such as automobiles and power storage facilities, and development for these fields has been actively promoted.

リチウム二次電池用の正極活物質としては、コバルト酸リチウム（ＬｉＣｏＯ２）が広く利用されているが、主原料であるコバルトが高価である上に資源の枯渇等による供給不安が指摘されている。これに対して、リチウム遷移金属複合酸化物（化学式：Ｌｉ１＋ｘＮｉｙＣｏｚＭｎ１−ｘ−ｙ−ｚＯ２）はコバルトの使用量が少なく、代替となるニッケル、マンガンは資源が比較的豊富である上に経済性の面からも有利であり、その将来性が期待されている。 As a positive electrode active material for a lithium secondary battery, lithium cobaltate (LiCoO 2 ) is widely used. However, the main raw material cobalt is expensive and supply instability due to resource depletion has been pointed out. . On the other hand, lithium transition metal composite oxide (chemical formula: Li 1 + x Ni y Co z Mn 1-xyz O 2 ) uses a small amount of cobalt, and alternative nickel and manganese have relatively less resources. In addition to being abundant, it is also advantageous in terms of economy, and its future is expected.

しかし、ニッケルを多く含むリチウム遷移金属複合酸化物を正極活物質として用いた場合、コバルト酸リチウムに比べ結晶構造が不安定であるため、充放電サイクルに伴う容量低下が大きいことが問題とされている。   However, when a lithium transition metal composite oxide containing a large amount of nickel is used as the positive electrode active material, the crystal structure is unstable compared to lithium cobaltate, so that there is a problem that the capacity drop accompanying the charge / discharge cycle is large. Yes.

このような欠点を解決するために、様々な提案がなされている。   Various proposals have been made to solve such drawbacks.

例えば特許文献１には充放電時における界面抵抗の低減、及びその効果による放電容量の向上、レート特性、サイクル特性の向上を目的として、リチウム遷移金属複合酸化物の粒子表面をａＬｉ２Ｏ−ＺｒＯ２（０．１≦ａ≦２．０）の組成の被覆材にて被覆した、一般式：Ｌｉ１−ｘ−ｙ−ｚＮｉｘＣｏｙＡｌｚＯ２またはＬｉ１−ｘ−ｙ−ｚＮｉｘＣｏｙＭｎｚＯ２（０＜ｘ＜１、０＜ｙ＜１、０＜ｚ＜１）で表されるリチウム遷移金属複合酸化物が提案されている。 For example, Patent Document 1 discloses that the surface of lithium transition metal composite oxide particles is aLi 2 O—ZrO for the purpose of reducing the interfacial resistance during charging and discharging, and improving the discharge capacity, rate characteristics, and cycle characteristics. 2 (0.1 ≦ a ≦ 2.0) coated with a coating material having a general formula: Li 1−x−yz Ni x Co y Al z O 2 or Li 1−x−yz A lithium transition metal composite oxide represented by Ni x Co y Mn z O 2 (0 <x <1, 0 <y <1, 0 <z <1) has been proposed.

また特許文献２では、サイクル特性や経年寿命を向上させることができる電池用正極活物質として、ＬｉｘＭＯｙ（式中のＭは、Ｃｏ、Ｎｉ、Ｍｎ、Ａｌ、Ｍｇの少なくとも一種を含む）で表されるリチウム遷移金属複合酸化物に酸化ジルコニウム粒子をメカノケミカル法によりリチウム含有複合酸化物の表面に形成、被覆層を構成することが提案されている。 In Patent Document 2, Li x MO y (M in the formula includes at least one of Co, Ni, Mn, Al, and Mg) as a positive electrode active material for a battery that can improve cycle characteristics and aging life. It has been proposed to form a coating layer by forming zirconium oxide particles on the surface of a lithium-containing composite oxide by a mechanochemical method on the lithium transition metal composite oxide represented by

さらに、正極活物質の表面を酸化ジルコニウムで被覆する手段として、特許文献３には、リチウム及び遷移金属からなる複合酸化物にジルコニウムイソプロポキシドを加水分解・重合反応をさせたジルコニアゾル水溶液を噴霧法で被覆し、加熱処理する方法が提案されている。   Further, as a means for coating the surface of the positive electrode active material with zirconium oxide, Patent Document 3 discloses spraying a zirconia sol aqueous solution obtained by hydrolyzing and polymerizing zirconium isopropoxide to a composite oxide composed of lithium and a transition metal. A method of coating with a method and heat-treating has been proposed.

特許文献４には、酸化ジルコニウムを添加することで、一部が主成分である遷移金属に固溶し、正極活物質の結晶内部でのＬｉの拡散が容易となるため、低温での出力特性が向上することが提案されている。   In Patent Document 4, the addition of zirconium oxide makes it partly dissolved in the transition metal, which is the main component, and facilitates the diffusion of Li inside the crystal of the positive electrode active material. It has been proposed to improve.

特開２０１４−１１６１４９号公報JP 2014-116149 A 特開２０１３−２３５６６６号公報JP2013-235666A 特開２００６−１５６０３２号公報JP 2006-156032 A 特許４７６６０４０号公報Japanese Patent No. 4766040

これらの製造方法によって得られたリチウム遷移金属複合酸化物は、充電容量および放電容量がともに高く、サイクル特性・出力特性も改善されている。しかしながら、いずれの文献においても添加するジルコニウム化合物については使用原料名のみの表記で、粒子形態については言及されていない。   Lithium transition metal composite oxides obtained by these production methods have both high charge capacity and discharge capacity, and improved cycle characteristics and output characteristics. However, in any document, the zirconium compound to be added is indicated only by the name of the raw material used, and the particle form is not mentioned.

本発明では、上記問題点に鑑みてなされたものであり、二次電池の高温サイクルにともなう抵抗上昇を抑え、放電容量及び放電電圧の低下が小さい二次電池用正極活物質としてのリチウム遷移金属複合酸化物及びその製造方法を提供することを目的とする。また、本発明では、低コストで量産性に優れたリチウム遷移金属複合酸化物の製造方法を提供することをも目的とする。   In the present invention, lithium transition metal as a positive electrode active material for a secondary battery, which has been made in view of the above problems, suppresses an increase in resistance accompanying a high temperature cycle of the secondary battery, and has a small decrease in discharge capacity and discharge voltage. An object is to provide a composite oxide and a method for producing the same. Another object of the present invention is to provide a method for producing a lithium transition metal composite oxide that is low in cost and excellent in mass productivity.

本発明者は、上記課題を解決すべく、種々検討し、リチウム遷移金属複合酸化物に比表面積が３０〜９０ｍ２／ｇの酸化ジルコニウムを混合、焼成しジルコニウム化合物を付着させることが、二次電池の高温サイクルにともなう抵抗上昇を抑え、放電容量及び放電電圧の低下を抑制するのに極めて効果的であることを見出し、本発明を完成した。 In order to solve the above-mentioned problems, the present inventor has made various studies, mixing a zirconium oxide having a specific surface area of 30 to 90 m 2 / g with a lithium transition metal composite oxide, firing and adhering a zirconium compound, The present invention has been completed by finding that it is extremely effective in suppressing an increase in resistance due to a high temperature cycle of a battery and suppressing a decrease in discharge capacity and discharge voltage.

本発明の要旨は、次の通りである。   The gist of the present invention is as follows.

（１）化学組成が一般式Ｌｉ１＋ｘＮｉｙＣｏｚＭｎ１−ｘ−ｙ−ｚ−ｗＭｗＯ２で表され、ここで、ＭはＡｌ，Ｍｇ，Ｗ及びＺｒから選ばれた１種又は２種以上の金属元素であり、ｘは−０．０５≦ｘ≦０．０５、ｙは０．３≦ｙ＜０．９、ｚは０．０５≦ｚ≦０．３５、ｗは０≦ｗ≦０．１の範囲をとるリチウム遷移金属複合酸化物に比表面積が３０〜９０ｍ２／ｇの酸化ジルコニウムが、前記リチウム遷移金属複合酸化物の粒子の表面に０．１〜１．０質量％付着した複合粒子からなる、最大粒子径が５０μｍ以下であることを特徴とするリチウム遷移金属複合酸化物。 (1) chemical composition represented by the general formula Li 1 + x Ni y Co z Mn 1-x-y-z-w M w O 2, wherein one M is selected from Al, Mg, W and Zr Or x is −0.05 ≦ x ≦ 0.05, y is 0.3 ≦ y <0.9, z is 0.05 ≦ z ≦ 0.35, and w is 0. In the lithium transition metal composite oxide having a range of ≦ w ≦ 0.1, zirconium oxide having a specific surface area of 30 to 90 m 2 / g is 0.1 to 1.0 on the surface of the lithium transition metal composite oxide particles. A lithium transition metal composite oxide comprising composite particles adhered by mass% and having a maximum particle diameter of 50 μm or less.

（２）リチウム塩及び遷移金属複合水酸化物と同時に、または順に比表面積が３０〜９０ｍ２／ｇの酸化ジルコニウムを乾式で混合し、ついで焼成温度が５００℃以上７００℃以下に保持される第一の焼成工程と、前記第一の焼成工程から焼成温度を下げずに引き続き行われ、焼成温度が７００℃以上１０００℃以下に保持される第二の焼成工程または前記第一の焼成工程から焼成温度を一旦室温まで下げた後、焼成温度が７００℃以上１０００℃以下に保持される第二の焼成工程により焼成することを特徴とする上記（１）に記載のリチウム遷移金属複合酸化物の製造方法。 (2) Zirconium oxide having a specific surface area of 30 to 90 m 2 / g is mixed with a lithium salt and a transition metal composite hydroxide simultaneously or sequentially, and then the firing temperature is maintained at 500 ° C. or more and 700 ° C. or less. One firing step and the second firing step that is performed continuously without lowering the firing temperature from the first firing step, and the firing temperature is maintained at 700 ° C. or more and 1000 ° C. or less, or firing from the first firing step. The lithium transition metal composite oxide according to (1), wherein the temperature is once lowered to room temperature and then fired in a second firing step in which the firing temperature is maintained at 700 ° C. or higher and 1000 ° C. or lower. Method.

（３） 前記リチウム塩及び遷移金属複合水酸化物と混合する前記酸化ジルコニウムの添加量がリチウム遷移金属複合酸化物の０．１〜１．０質量％であることを特徴とする上記（２）に記載のリチウム遷移金属複合酸化物の製造方法。   (3) The above (2), wherein the addition amount of the zirconium oxide mixed with the lithium salt and the transition metal composite hydroxide is 0.1 to 1.0% by mass of the lithium transition metal composite oxide. A process for producing a lithium transition metal composite oxide as described in 1 above.

（４） 前記一般式Ｌｉ１＋ｘＮｉｙＣｏｚＭｎ１−ｘ−ｙ−ｚ−ｗＭｗＯ２で表されるリチウム遷移金属複合酸化物となるように、リチウム塩及び遷移金属複合化合物を混合し、ここで同時に、または順に比表面積が３０〜９０ｍ２／ｇの酸化ジルコニウム粒子を混合して、混合粉を焼成させることにより前記リチウム遷移金属複合酸化物の表面に酸化ジルコニウムが付着した複合粒子にすることを特徴とする上記（２）または（３）に記載のリチウム遷移金属複合酸化物の製造方法。 (4) A lithium salt and a transition metal composite compound are mixed so as to be a lithium transition metal composite oxide represented by the general formula Li 1 + x Ni y Co z Mn 1-xyz-w M w O 2 Here, the composite particles in which zirconium oxide is adhered to the surface of the lithium transition metal composite oxide by mixing the zirconium oxide particles having a specific surface area of 30 to 90 m 2 / g at the same time or sequentially and firing the mixed powder. The method for producing a lithium transition metal composite oxide according to the above (2) or (3), wherein

本発明により、リチウム遷移金属複合酸化物の表面に比表面積が３０〜９０ｍ２／ｇの酸化ジルコニウムを付着させることで、リチウム遷移金属複合酸化物を高温環境下に置いたときの充放電サイクルに伴う抵抗上昇を抑え、放電容量及び放電電圧の低下抑制が可能になる効果を奏する。この効果が得られるはっきりとした理由は不明であるが、リチウム遷移金属複合酸化物に比表面積の大きい酸化ジルコニウム微粉を付着させることで必要以上のリチウムの脱挿入によるＮｉの価数変化を抑制し、結晶構造が崩れにくくなり、放電サイクルに伴う抵抗上昇を抑え、放電容量及び放電電圧の低下を抑えるものと推定される。 According to the present invention, by attaching zirconium oxide having a specific surface area of 30 to 90 m 2 / g to the surface of the lithium transition metal composite oxide, the charge / discharge cycle when the lithium transition metal composite oxide is placed in a high temperature environment is achieved. It is possible to suppress the accompanying increase in resistance and to suppress the decrease in discharge capacity and discharge voltage. The clear reason why this effect is obtained is unknown, but by attaching zirconium oxide fine powder with a large specific surface area to the lithium transition metal composite oxide, the change in the valence of Ni due to excessive lithium desorption is suppressed. It is presumed that the crystal structure is less likely to collapse, the resistance increase accompanying the discharge cycle is suppressed, and the decrease in discharge capacity and discharge voltage is suppressed.

実施例１〜７および比較例１〜３のサイクル評価後のコイン型リチウム二次電池について、インピーダンス測定し、複素平面上にプロットした、いわゆるコールコールプロットと称される図である。It is a figure called what is called a Cole-Cole plot which measured impedance about the coin-type lithium secondary battery after cycle evaluation of Examples 1-7 and Comparative Examples 1-3, and plotted on the complex plane. 実施例８、９および比較例６、７のサイクル評価後のコイン型リチウム二次電池について、インピーダンス測定し、複素平面上にプロットした、いわゆるコールコールプロットと称される図である。It is a figure called what is called a Cole-Cole plot which measured impedance about the coin-type lithium secondary battery after the cycle evaluation of Examples 8 and 9 and Comparative Examples 6 and 7, and plotted on a complex plane. 実施例１〜３および比較例１のサイクル毎の平均放電電圧について、放電電圧維持率を比較した図である。It is the figure which compared the discharge voltage maintenance factor about the average discharge voltage for every cycle of Examples 1-3 and the comparative example 1. FIG.

以下本発明を詳細に説明する。   The present invention will be described in detail below.

本発明者は、二次電池用正極活物質としてのリチウム遷移金属複合酸化物粒子に、比表面積が３０〜９０ｍ２／ｇの酸化ジルコニウムを付着させると、高温サイクルにともなう二次電池の抵抗上昇が小さく、放電容量及び放電電圧の低下が抑制され、極めて効果的であることを見出し、本発明を完成した。 When the present inventors attach zirconium oxide having a specific surface area of 30 to 90 m 2 / g to lithium transition metal composite oxide particles as a positive electrode active material for a secondary battery, the resistance of the secondary battery increases with a high-temperature cycle. The present invention has been completed by discovering that the discharge capacity and the decrease in the discharge voltage are suppressed and extremely effective.

本発明で好適に用いることができるリチウム遷移金属複合酸化物は、化学組成が一般式Ｌｉ１＋ｘＮｉｙＣｏｚＭｎ１−ｘ−ｙ−ｚ−ｗＭｗＯ２で表され、ここで、ＭはＡｌ，Ｍｇ，Ｗ及びＺｒから選ばれた１種又は２種以上の金属元素であり、ｘは−０．０５≦ｘ≦０．０５、ｙは０．３≦ｙ＜０．９、ｚは０．０５≦ｚ≦０．３５、ｗは０≦ｗ≦０．１の範囲をとるリチウム遷移金属複合酸化物である。 Lithium transition metal complex oxide can be suitably used in the present invention, the chemical composition is represented by the general formula Li 1 + x Ni y Co z Mn 1-x-y-z-w M w O 2, where, M Is one or more metal elements selected from Al, Mg, W and Zr, x is −0.05 ≦ x ≦ 0.05, y is 0.3 ≦ y <0.9, z Is a lithium transition metal complex oxide in the range of 0.05 ≦ z ≦ 0.35 and w is in the range of 0 ≦ w ≦ 0.1.

また、ここで、−０．０５≦ｘ≦０．０５としたのは、ｘ＜−０．０５では、Ｌｉ層に入るＮｉが多くなり、リチウム遷移金属複合酸化物の放電容量が小さくなるためであり、ｘ＞０．０５では、過剰なＬｉが遷移金属層に入り、Ｎｉ価数を高め、放電容量の低下を引き起こす原因となるためで、０．３≦ｙ＜０．９としたのは、Ｎｉ価数変化を用いた正極材料であるためで、０．０５≦ｚ≦０．３５としたのは、結晶構造安定化のためにＮｉ量に応じた必要量としたものである。   Here, −0.05 ≦ x ≦ 0.05 is set because, when x <−0.05, more Ni enters the Li layer and the discharge capacity of the lithium transition metal composite oxide becomes smaller. When x> 0.05, excessive Li enters the transition metal layer, increases the Ni valence, and causes a decrease in discharge capacity, so 0.3 ≦ y <0.9. Is a positive electrode material using Ni valence change, and 0.05 ≦ z ≦ 0.35 is set to a necessary amount corresponding to the amount of Ni for stabilizing the crystal structure.

上記リチウム遷移金属複合酸化物Ｌｉ１＋ｘＮｉｙＣｏｚＭｎ１−ｘ−ｙ−ｚ−ｗＭｗＯ２におけるＭは、高温特性の改善に効果があるものとして選択され、Ａｌ，Ｍｇ，Ｗ及びＺｒから選ばれた１種又は２種以上の金属元素であり、ｗは０≦ｗ≦０．１の範囲が好ましい。ｗ≧０．１とした場合、放電容量が低下し好ましくない。 M in the lithium transition metal composite oxide Li 1 + x Ni y Co z Mn 1-xyzw M w O 2 is selected as having an effect of improving high temperature characteristics, and Al, Mg, W and It is one or more metal elements selected from Zr, and w is preferably in the range of 0 ≦ w ≦ 0.1. When w ≧ 0.1, the discharge capacity decreases, which is not preferable.

本発明のリチウム遷移金属複合酸化物は、上記リチウム遷移金属複合酸化物の粒子の表面に、比表面積が３０〜９０ｍ２／ｇの酸化ジルコニウムが０．１〜１．０質量％付着した複合粒子からなり、最大粒子径が５０μｍ以下であることを特徴とする。 The lithium transition metal composite oxide of the present invention is a composite particle in which 0.1 to 1.0% by mass of zirconium oxide having a specific surface area of 30 to 90 m 2 / g is attached to the surface of the lithium transition metal composite oxide particle. The maximum particle size is 50 μm or less.

酸化ジルコニウムの比表面積を３０〜９０ｍ２／ｇとするのは、比表面積が３０ｍ２／ｇより小さいと、酸化ジルコニウムの粒子数が少なく、リチウム遷移金属複合酸化物との接触面が小さくなるため、リチウム遷移金属複合酸化物粒子表面への均一な付着が困難になる。一方、９０ｍ２／ｇより大きい場合では遷移金属複合化合物やリチウム塩との混合前に酸化ジルコニウム同士が凝集してしまい、リチウム遷移金属複合酸化物の粒子表面への均一な付着が困難になる問題を生ずるからである。なお酸化ジルコニウムの比表面積の測定にはマウンテック社のＭａｃｓｏｒｂ ＨＭ ｍｏｄｅｌ−１２０８を使用した。 To a specific surface area of the zirconium oxide and 30~90m 2 / g has a specific surface area of 30 m 2 / g less, small number of particles of zirconium oxide, since the contact surface with the lithium-transition metal composite oxide is reduced Further, uniform adhesion to the surface of the lithium transition metal composite oxide particles becomes difficult. On the other hand, when it is larger than 90 m 2 / g, zirconium oxide aggregates before mixing with the transition metal composite compound or the lithium salt, making it difficult to uniformly adhere the lithium transition metal composite oxide to the particle surface. It is because it produces. For measurement of the specific surface area of zirconium oxide, Macsorb HM model-1208 manufactured by Mountec Co., Ltd. was used.

酸化ジルコニウムが０．１〜１．０質量％付着した複合粒子とするのは、付着量が０．１質量％より小さいと、二次電池を高温環境下に置いたときの充放電サイクルに伴う抵抗上昇の抑制、放電容量及び放電電圧の低下抑制効果が見られない。下限を０．１質量％とするが、０．２質量％以上がより好ましい。一方、付着量が１．０質量％を超えて大きい場合、初期容量・充放電効率が低下してしまう問題を生ずる。為そのため０．１〜１．０質量％とする。   The composite particles having 0.1 to 1.0% by mass of zirconium oxide adhere to the charge / discharge cycle when the secondary battery is placed in a high temperature environment when the amount of adhesion is less than 0.1% by mass. Suppression of resistance rise, discharge capacity and reduction of discharge voltage are not observed. Although a minimum is 0.1 mass%, 0.2 mass% or more is more preferable. On the other hand, when the adhesion amount is larger than 1.0% by mass, there arises a problem that the initial capacity / charge / discharge efficiency is lowered. Therefore, the content is 0.1 to 1.0% by mass.

次に、本発明のリチウム遷移金属複合酸化物の製造方法について説明する。   Next, the manufacturing method of the lithium transition metal complex oxide of this invention is demonstrated.

本発明に係るリチウム遷移金属複合酸化物の製造方法は、一般式Ｌｉ１＋ｘＮｉｙＣｏｚＭｎ１−ｘ−ｙ−ｚ−ｗＭｗＯ２で表されるリチウム遷移金属複合酸化物となるように、リチウム塩及び遷移金属複合化合物を混合し、ここで同時に、または順に比表面積が３０〜９０ｍ２／ｇの酸化ジルコニウム粒子を乾式で混合する段階と、ついで焼成温度が５００℃以上７００℃以下に保持される第一の焼成工程と、前記第一の焼成工程から焼成温度を下げずに引き続き行われ、焼成温度が７００℃以上１０００℃以下に保持される第二の焼成工程または前記第一の焼成工程から焼成温度を一旦室温まで下げた後、焼成温度が７００℃以上１０００℃以下に保持される第二の焼成工程を行う工程とを、順次行うことを特徴とする。 The method for producing a lithium transition metal composite oxide according to the present invention is a lithium transition metal composite oxide represented by the general formula Li 1 + x Ni y Co z Mn 1−x−y−z−w M w O 2. In addition, a lithium salt and a transition metal composite compound are mixed, and here, simultaneously or sequentially, zirconium oxide particles having a specific surface area of 30 to 90 m 2 / g are mixed in a dry process, and then the firing temperature is 500 ° C. or more and 700 ° C. or less The first baking step held in the first baking step, the second baking step that is performed continuously without lowering the baking temperature from the first baking step, and the baking temperature is maintained at 700 ° C. or higher and 1000 ° C. or lower, or the first From the firing step, the firing temperature is once lowered to room temperature, and then the second firing step in which the firing temperature is maintained at 700 ° C. or higher and 1000 ° C. or lower is sequentially performed.

一般式Ｌｉ１＋ｘＮｉｙＣｏｚＭｎ１−ｘ−ｙ−ｚ−ｗＭｗＯ２で表されるリチウム遷移金属複合酸化物とするには、まず遷移金属複合化合物を準備する。その際、化学組成が一般式：ＮｉｙＣｏｚＭｎ１−ｙ−ｚ−ｗＭｗ（ＯＨ）２で表される遷移金属複合水酸化物が特に好適である。上記一般式から明らかなように、典型的なリチウム遷移金属複合酸化物（化学式：Ｌｉ１＋ｘＮｉｙＣｏｚＭｎ１−ｘ−ｙ−ｚＯ２）の遷移金属に対してＬｉをやや過剰に含むものも含まれる。 In order to obtain a lithium transition metal composite oxide represented by the general formula Li 1 + x Ni y Co z Mn 1-xy-z-w M w O 2 , first, a transition metal composite compound is prepared. At that time, a transition metal composite hydroxide having a chemical composition represented by the general formula: Ni y Co z Mn 1-yz w M w (OH) 2 is particularly suitable. As apparent from the above general formula, typical lithium-transition metal composite oxide: slight excess containing Li with respect to (Formula Li 1 + x Ni y Co z Mn 1-x-y-z O 2) transition metals Also included.

用いるリチウム塩としては特に指定はないが炭酸リチウム、水酸化リチウムが好ましい。ｙ＜０．６においては炭酸リチウムが好適であり、ｙが０．６以上では水酸化リチウムが適している。また、リチウム塩の粒径は、遷移金属複合化合物との反応性を考慮すると、平均粒子径で１０μｍ以下が好ましい。   The lithium salt to be used is not particularly specified, but lithium carbonate and lithium hydroxide are preferable. Lithium carbonate is suitable when y <0.6, and lithium hydroxide is suitable when y is 0.6 or more. Further, the particle diameter of the lithium salt is preferably 10 μm or less in terms of average particle diameter in consideration of reactivity with the transition metal composite compound.

酸化ジルコニウムは、リチウム遷移金属複合酸化物に対し、０．１〜１．０質量％添加混合する。添加量が０．１質量％より小さいと、二次電池を高温環境下に置いたときの充放電サイクルに伴う抵抗上昇の抑制、放電容量及び放電電圧の低下抑制効果が見られない。一方、１．０質量％を超えて大きい場合は初期容量・充放電効率が低下してしまう問題を生ずる。   Zirconium oxide is added and mixed in an amount of 0.1 to 1.0 mass% with respect to the lithium transition metal composite oxide. When the addition amount is less than 0.1% by mass, the effect of suppressing the increase in resistance accompanying the charge / discharge cycle when the secondary battery is placed in a high temperature environment, and the effect of suppressing the decrease in discharge capacity and discharge voltage are not observed. On the other hand, when it exceeds 1.0 mass%, the problem which initial capacity and charging / discharging efficiency fall will arise.

混合工程に引き続いて焼成工程を行うが、焼成工程は、焼成温度が５００℃以上７００℃以下に保持される第一の焼成工程と、前記第一の焼成工程から焼成温度を下げずに引き続き行われ、焼成温度が７００℃以上１０００℃以下に保持される第二の焼成工程または前記第一の焼成工程から焼成温度を一旦室温まで下げた後、焼成温度が７００℃以上１０００℃以下に保持される第二の焼成工程を行う。   The firing process is performed subsequent to the mixing process. The firing process is performed by a first firing process in which the firing temperature is maintained at 500 ° C. or more and 700 ° C. or less, and the firing process is continuously performed without lowering the firing temperature from the first firing process. After the firing temperature is temporarily lowered to room temperature from the second firing step in which the firing temperature is maintained at 700 ° C. or higher and 1000 ° C. or lower, the firing temperature is maintained at 700 ° C. or higher and 1000 ° C. or lower. The second firing step is performed.

第一の焼成工程では５００〜７００℃で２〜１０時間焼成する。５００〜７００℃とするのはＬｉ塩と遷移金属複合化合物の反応がこの温度域で起こる為である。   In the first baking step, baking is performed at 500 to 700 ° C. for 2 to 10 hours. The reason for setting the temperature to 500 to 700 ° C. is that the reaction between the Li salt and the transition metal composite compound occurs in this temperature range.

第二の焼成工程では反応促進のため第一の焼成工程より高い７００〜１０００℃で５〜３０時間焼成する。１０００℃以上では一次粒子の成長や粒子同士の焼結が進み好ましくない。７００℃未満では一次粒子が十分に成長せず、結晶性が低くなる。また目的の組成が得られなくなるため好ましくない。   In the second baking step, baking is performed at 700 to 1000 ° C., which is higher than that in the first baking step, for 5 to 30 hours to promote the reaction. When the temperature is 1000 ° C. or higher, the growth of primary particles and the sintering of particles progress, which is not preferable. If it is less than 700 degreeC, a primary particle will not fully grow and crystallinity will become low. Moreover, since the target composition cannot be obtained, it is not preferable.

好適な焼成時間は温度との組み合わせで一概には定まらないが第一の焼成工程では２〜１０時間が好ましく、第二の焼成工程では５〜３０時間が好ましい。   The preferred firing time is not generally determined by the combination with the temperature, but is preferably 2 to 10 hours in the first firing step, and preferably 5 to 30 hours in the second firing step.

合成（焼成）されたリチウム遷移金属複合酸化物は、最大粒子径が５０μｍ以下に粒度調整する。最大粒子径が５０μｍを超えると、粒子のばらつきが大きくなり、充放電中に熱が発生しやすくなり劣化してしまう問題を生ずる。なお、粒度調整手段は、特に問うことなく、例えば、ロールミル、ジェットミル、フルイ等を用いることができる。   The synthesized (baked) lithium transition metal composite oxide is adjusted in particle size to a maximum particle size of 50 μm or less. When the maximum particle diameter exceeds 50 μm, the dispersion of the particles becomes large, which causes a problem that heat is easily generated during charge / discharge and deteriorates. For example, a roll mill, a jet mill, a sieve or the like can be used as the particle size adjusting means without any particular question.

本発明に係る上記リチウム遷移金属複合酸化物を正極活物質として使用する場合にも、通常のリチウム遷移金属複合酸化物と同様、負極活物質には炭素材料、リチウム吸蔵合金等のリチウム吸蔵放出可能な物質を用い、電解液としてはリチウム塩を非水系電解液または樹脂に溶解した非水系電解液を用いる。たとえばリチウム塩として六フッ化リン酸リチウム（ＬｉＰＦ６）を用い、非水系電解液としてエチレンカーボネートとジエチルカーボネートの混合溶液を用いる。このほかにもリチウム塩としてはＬｉＣｌＯ４、ＬｉＡｓＦ６、ＬｉＢＦ４、ＬｉＳＯ３ＣＦ３、ＬｉＮ（ＳＯ３ＣＦ３）２などやそれらの混合物が用いられる。また、非水電解液としてはジエチルカーボネート、プロピレンカーボネート、ビニレンカーボネート等やその混合物、及びポリエチレンイミン等を主鎖とした高いイオン伝導性を有する高分子固体電解質（樹脂）等を用いることが可能である。 Even when the lithium transition metal composite oxide according to the present invention is used as a positive electrode active material, the negative electrode active material can store and release lithium such as carbon materials and lithium storage alloys, as in the case of a normal lithium transition metal composite oxide. As the electrolytic solution, a non-aqueous electrolytic solution obtained by dissolving a lithium salt in a resin or a resin is used. For example, lithium hexafluorophosphate (LiPF6) is used as the lithium salt, and a mixed solution of ethylene carbonate and diethyl carbonate is used as the non-aqueous electrolyte. In addition, LiClO 4 , LiAsF 6 , LiBF 4 , LiSO 3 CF 3 , LiN (SO 3 CF 3 ) 2 , or a mixture thereof may be used as the lithium salt. Further, as the non-aqueous electrolyte, diethyl carbonate, propylene carbonate, vinylene carbonate, or a mixture thereof, and a polymer solid electrolyte (resin) having high ionic conductivity with polyethyleneimine as a main chain can be used. is there.

以下本発明を実施例比較例により説明する。なお、本発明は実施例に限定されるものではない。   Hereinafter, the present invention will be described by way of comparative examples. In addition, this invention is not limited to an Example.

（実施例１）
化学式Ｌｉ１．０２Ｎｉ０．４９Ｃｏ０．２０Ｍｎ０．２９Ｏ２となるよう調整した炭酸リチウム、遷移金属複合化合物（化学式：Ｎｉ０．５Ｃｏ０．２Ｍｎ０．３（ＯＨ）２）に、比表面積が６０ｍ２／ｇの酸化ジルコニウムをリチウム遷移金属複合酸化物に対し０．５質量％の比率になるように加え、精密混合機で乾式混合、その後、６５０℃で３時間、引き続き８７０℃で８時間焼成し酸化ジルコニウムが付着したリチウム遷移金属複合酸化物を合成した。得られたリチウム遷移金属複合酸化物を、最大粒子径が５０μｍ以下になるように解砕し、実施例１活物質を作製した。 Example 1
Formula Li 1.02 Ni 0.49 Co 0.20 Mn 0.29 O 2 and comprising as adjusted lithium carbonate, a transition metal complex compound (Formula: Ni 0.5 Co 0.2 Mn 0.3 ( OH) 2 ), Zirconium oxide having a specific surface area of 60 m 2 / g is added so as to have a ratio of 0.5 mass% with respect to the lithium transition metal composite oxide, dry-mixed with a precision mixer, and then at 650 ° C. for 3 hours. Subsequently, it was baked at 870 ° C. for 8 hours to synthesize a lithium transition metal composite oxide to which zirconium oxide was adhered. The obtained lithium transition metal composite oxide was crushed so that the maximum particle size was 50 μm or less, and an active material of Example 1 was produced.

（電池作製）
得られた実施例１活物質を用い、導電材としてアセチレンブラック、結着剤としてクレハ株式会社製ＫＦポリマー＃１１２０をそれぞれ用い、活物質：導電材：結着材の比を９０：６：４（質量比）で混練し、正極スラリーを作製した。このスラリーをアルミニウム製の集電体にドクターブレード法により塗布し、乾燥後、直径１１ｍｍ、厚さ０．３ｍｍの円盤状に打ち抜き、正極を作製した。それを圧力２０ＭＰａで加圧成形し、１２０℃で８時間の減圧乾燥を行い、正極板とした。負極には厚さ０．２１ｍｍの金属リチウムを約１５ｍｍ四方に切り抜いたものを使用し、電解液にはエチレンカーボネートとジエチルカーボネート体積比３：７の混合溶媒に溶質ＬｉＰＦ６を１モルの割合で溶解したものを使用し、セパレータには多孔質ポリプロピレン膜を用い、直径２０ｍｍ、高さ３．２ｍｍのＣＲ２０３２タイプ（宝泉株式会社製の部品キャップ、ケース、ガスケット、スペーサ、及びウェーブワッシャーを使用）のコイン型リチウム二次電池を作製した。 (Battery production)
Example 1 The obtained active material was used, acetylene black was used as the conductive material, and KF polymer # 1120 manufactured by Kureha Corporation was used as the binder, and the ratio of active material: conductive material: binder was 90: 6: 4. (Mass ratio) knead | mixed and produced the positive electrode slurry. This slurry was applied to an aluminum current collector by a doctor blade method, dried, and then punched into a disk shape having a diameter of 11 mm and a thickness of 0.3 mm to produce a positive electrode. It was pressure-molded at a pressure of 20 MPa and dried under reduced pressure at 120 ° C. for 8 hours to obtain a positive electrode plate. For the negative electrode, 0.21 mm thick metal lithium cut out about 15 mm square was used. For the electrolyte, 1 mol of solute LiPF6 was dissolved in a mixed solvent of ethylene carbonate and diethyl carbonate in a volume ratio of 3: 7. CR2032 type (uses parts cap, case, gasket, spacer and wave washer manufactured by Hosen Co., Ltd.) with a diameter of 20 mm and a height of 3.2 mm using a porous polypropylene membrane as a separator. A coin-type lithium secondary battery was produced.

作製したコイン型リチウム二次電池を、まず２５℃の恒温槽内にて、初回充電容量・初回充放電効率を測定した。充電は、レート３５ｍＡ／ｇ、上限４．２５Ｖ定電流定電圧で電流が２ｍＡ／ｇとなった時点で充電を終了した。放電は、レート３５ｍＡ／ｇ、放電下限電圧３．０Ｖとした。初回充放電効率とは、初回の放電容量を初回充電容量で除算した割合（％）で算出した。   First, the initial charge capacity and initial charge / discharge efficiency of the produced coin-type lithium secondary battery were measured in a constant temperature bath at 25 ° C. Charging was terminated when the current became 2 mA / g at a rate of 35 mA / g and an upper limit of 4.25 V constant current and constant voltage. Discharge was performed at a rate of 35 mA / g and a discharge lower limit voltage of 3.0V. The initial charge / discharge efficiency was calculated as a ratio (%) obtained by dividing the initial discharge capacity by the initial charge capacity.

次に、前記初回容量測定後のコイン型リチウム二次電池を４５℃の恒温槽内にて、充電と放電電流を８０ｍＡ／ｇ、電位範囲３．０Ｖ〜４．３Ｖで１２０回の繰返し充放電試験を行った。初回充電容量・初回充放電効率、１２０サイクル中の最大放電容量を１サイクル目と設定し、その１００サイクル後の放電容量維持率の結果を表１に示す。また、サイクル毎の平均放電電圧について、放電電圧維持率で比較した結果を図３に示す。   Next, the coin-type lithium secondary battery after the initial capacity measurement is repeatedly charged and discharged 120 times in a constant temperature bath at 45 ° C. with a charge and discharge current of 80 mA / g and a potential range of 3.0 V to 4.3 V. A test was conducted. The initial charge capacity / initial charge / discharge efficiency and the maximum discharge capacity during 120 cycles are set as the first cycle, and the results of the discharge capacity maintenance rate after 100 cycles are shown in Table 1. Moreover, the result of having compared by the discharge voltage maintenance factor about the average discharge voltage for every cycle is shown in FIG.

前記記載のサイクル評価後のコイン型リチウム二次電池を２５℃の恒温槽内にてＳＯＣ１００％まで充電を行い、インピーダンス測定を行った。測定装置として、Ｂｉｏ−Ｌｏｇｉｃ社製ＶＳＰを使用した。測定条件は振幅を±１０ｍＶ、周波数を２００ｋＨｚ〜１０ｍＨｚの範囲で測定した。測定結果を複素平面上にプロットし、コールコールプロットを作成した。その結果を図１に示す。   The coin-type lithium secondary battery after the cycle evaluation described above was charged to SOC 100% in a constant temperature bath at 25 ° C., and impedance measurement was performed. Bio-Logic VSP was used as a measuring device. The measurement conditions were an amplitude of ± 10 mV and a frequency of 200 kHz to 10 mHz. The measurement results were plotted on a complex plane to create a Cole-Cole plot. The result is shown in FIG.

（実施例２）
酸化ジルコニウムとして比表面積が９０ｍ２／ｇのものを用いたことを除き、実施例１と同様にして実施例２活物質を作製した。 (Example 2)
An active material of Example 2 was prepared in the same manner as in Example 1 except that zirconium oxide having a specific surface area of 90 m2 / g was used.

コイン型リチウム二次電池を作製し、実施例１と同様に初回充電容量・初回充放電効率及び放電容量維持率、インピーダンス測定を実施した。その結果を、表１、図１に併せて示す。また、サイクル毎の平均放電電圧について、放電電圧維持率で比較した結果を図３に併せて示す。   A coin-type lithium secondary battery was prepared, and the initial charge capacity, the initial charge / discharge efficiency, the discharge capacity retention ratio, and the impedance were measured in the same manner as in Example 1. The results are also shown in Table 1 and FIG. Moreover, the result of having compared by the discharge voltage maintenance factor about the average discharge voltage for every cycle is combined with FIG. 3, and is shown.

（実施例３）
酸化ジルコニウムとして比表面積が３０ｍ２／ｇのものを用いたことを除き、実施例１と同様にして実施例３活物質を作製した。同様にコイン型リチウム二次電池を作製し、初回充電容量・初回充放電効率及び放電容量維持率、インピーダンス測定を実施した。その結果を、表１、図１に併せて示す。また、サイクル毎の平均放電電圧について、放電電圧維持率で比較した結果を図３に併せて示す。 (Example 3)
Example 3 active material was prepared in the same manner as in Example 1 except that zirconium oxide having a specific surface area of 30 m2 / g was used. Similarly, a coin-type lithium secondary battery was prepared, and the initial charge capacity, the initial charge / discharge efficiency, the discharge capacity retention ratio, and the impedance were measured. The results are also shown in Table 1 and FIG. Moreover, the result of having compared by the discharge voltage maintenance factor about the average discharge voltage for every cycle is combined with FIG. 3, and is shown.

(実施例４)
遷移金属複合化合物として、化学式：Ｎｉ０．５Ｃｏ０．２Ｍｎ０．２５Ａｌ０．０５（ＯＨ）２を用いたことを除き、実施例１と同様にして実施例４活物質を作製した。同様にコイン型リチウム二次電池を作製し、初回充電容量・初回充放電効率及び放電容量維持率、インピーダンス測定を実施した。その結果を、表１、図１に併せて示す。 Example 4
An active material of Example 4 was prepared in the same manner as in Example 1 except that the chemical formula: Ni 0.5 Co 0.2 Mn 0.25 Al 0.05 (OH) 2 was used as the transition metal composite compound. . Similarly, a coin-type lithium secondary battery was prepared, and the initial charge capacity, the initial charge / discharge efficiency, the discharge capacity retention ratio, and the impedance were measured. The results are also shown in Table 1 and FIG.

(実施例５)
遷移金属複合化合物として、化学式：Ｎｉ０．５Ｃｏ０．２Ｍｎ０．２７Ｍｇ０．０３（ＯＨ）２を用いたことを除き、実施例１と同様にして実施例５活物質を作製した。同様にコイン型リチウム二次電池を作製し、初回充電容量・初回充放電効率及び放電容量維持率、インピーダンス測定を実施した。その結果を、表１、図１に併せて示す。 (Example 5)
An active material of Example 5 was prepared in the same manner as in Example 1 except that the chemical formula: Ni 0.5 Co 0.2 Mn 0.27 Mg 0.03 (OH) 2 was used as the transition metal composite compound. . Similarly, a coin-type lithium secondary battery was prepared, and the initial charge capacity, the initial charge / discharge efficiency, the discharge capacity retention ratio, and the impedance were measured. The results are also shown in Table 1 and FIG.

(実施例６)
遷移金属複合化合物として、化学式：Ｎｉ０．５Ｃｏ０．２Ｍｎ０．２９Ｗ０．０１（ＯＨ）２を用いたことを除き、実施例１と同様にして実施例６活物質を作製した。同様にコイン型リチウム二次電池を作製し、初回充電容量・初回充放電効率及び放電容量維持率、インピーダンス測定を実施した。その結果を、表１、図１に併せて示す。 Example 6
An active material of Example 6 was prepared in the same manner as in Example 1 except that the chemical formula: Ni 0.5 Co 0.2 Mn 0.29 W 0.01 (OH) 2 was used as the transition metal composite compound. . Similarly, a coin-type lithium secondary battery was prepared, and the initial charge capacity, the initial charge / discharge efficiency, the discharge capacity retention ratio, and the impedance were measured. The results are also shown in Table 1 and FIG.

(実施例７)
遷移金属複合化合物として、化学式：Ｎｉ０．５Ｃｏ０．２Ｍｎ０．２９Ｚｒ０．０１（ＯＨ）２を用いたことを除き、実施例１と同様にして実施例７活物質を作製した。同様にコイン型リチウム二次電池を作製し、初回充電容量・初回充放電効率及び放電容量維持率、インピーダンス測定を実施した。その結果を、表１、図１に併せて示す。 (Example 7)
An active material of Example 7 was prepared in the same manner as in Example 1 except that the chemical formula: Ni 0.5 Co 0.2 Mn 0.29 Zr 0.01 (OH) 2 was used as the transition metal composite compound. . Similarly, a coin-type lithium secondary battery was prepared, and the initial charge capacity, the initial charge / discharge efficiency, the discharge capacity retention ratio, and the impedance were measured. The results are also shown in Table 1 and FIG.

(実施例８)
化学式Ｌｉ１．０１Ｎｉ０．３３Ｃｏ０．３３Ｍｎ０．３３Ｏ２となるように炭酸リチウム、遷移金属複合化合物（化学式：Ｎｉ１／３Ｃｏ１／３Ｍｎ１／３（ＯＨ）２）、比表面積が６０ｍ２／ｇの酸化ジルコニウムをリチウム遷移金属複合酸化物に対し０．５質量％の比率になるように加え、精密混合機で乾式混合を行った。その後、６５０℃で３時間、引き続き９５０℃で１５時間焼成し酸化ジルコニウムが付着したリチウム遷移金属複合酸化物を合成した。得られたリチウム遷移金属複合酸化物を、最大粒子径が５０μｍ以下になるように解砕し、実施例８の活物質を作製した。 (Example 8)
Lithium carbonate, transition metal composite compound (chemical formula: Ni 1/3 Co 1/3 Mn 1/3 (OH) 2 ) so as to have chemical formula Li 1.01 Ni 0.33 Co 0.33 Mn 0.33 O 2 Zirconium oxide having a specific surface area of 60 m 2 / g was added so as to have a ratio of 0.5 mass% with respect to the lithium transition metal composite oxide, and dry mixing was performed with a precision mixer. Thereafter, a lithium transition metal composite oxide to which zirconium oxide was adhered was synthesized by firing at 650 ° C. for 3 hours and subsequently at 950 ° C. for 15 hours. The obtained lithium transition metal composite oxide was crushed so that the maximum particle size was 50 μm or less, and an active material of Example 8 was produced.

同様にコイン型リチウム二次電池を作製し、初回充電容量・初回充放電効率及び放電容量維持率、インピーダンス測定を実施した。その結果を、表１、図２に併せて示す。   Similarly, a coin-type lithium secondary battery was prepared, and the initial charge capacity, the initial charge / discharge efficiency, the discharge capacity retention ratio, and the impedance were measured. The results are shown in Table 1 and FIG.

(実施例９)
化学式Ｌｉ１．０１Ｎｉ０．７９Ｃｏ０．１Ｍｎ０．１Ｏ２となるように水酸化リチウム一水和物、遷移金属複合化合物（化学式：Ｎｉ０．８Ｃｏ０．１Ｍｎ０．１（ＯＨ）２）、比表面積が６０ｍ２／ｇの酸化ジルコニウムをリチウム遷移金属複合酸化物に対し０．５質量％の比率になるように加え、精密混合機で乾式混合、その後、酸素フロー中で６００℃で５時間、引き続き７８０℃で２０時間焼成し、酸化ジルコニウムが付着したリチウム遷移金属複合酸化物を合成した。得られたリチウム遷移金属複合酸化物を、最大粒子径が５０μｍ以下になるように解砕し、実施例９の活物質を作製した。 Example 9
Lithium hydroxide monohydrate, transition metal complex compound (chemical formula: Ni 0.8 Co 0.1 Mn 0.1 so that the chemical formula Li 1.01 Ni 0.79 Co 0.1 Mn 0.1 O 2 (OH) 2 ), zirconium oxide having a specific surface area of 60 m 2 / g is added so as to have a ratio of 0.5 mass% with respect to the lithium transition metal composite oxide, dry-mixed with a precision mixer, and then in oxygen flow And then calcined at 600 ° C. for 5 hours and then at 780 ° C. for 20 hours to synthesize a lithium transition metal composite oxide having zirconium oxide attached thereto. The obtained lithium transition metal composite oxide was crushed so that the maximum particle size was 50 μm or less, and an active material of Example 9 was produced.

同様にコイン型リチウム二次電池を作製し、初回充電容量・初回充放電効率及び放電容量維持率、インピーダンス測定を実施した。その結果を、表１、図２に併せて示す。   Similarly, a coin-type lithium secondary battery was prepared, and the initial charge capacity, the initial charge / discharge efficiency, the discharge capacity retention ratio, and the impedance were measured. The results are shown in Table 1 and FIG.

（比較例１）
酸化ジルコニウムを添加しないことを除き、実施例１と同様にして比較例１活物質を作製した。同様にコイン型リチウム二次電池を作製し、初回充電容量・初回充放電効率及び放電容量維持率、インピーダンス測定を実施した。その結果を、表１、図１に併せて示す。また、サイクル毎の平均放電電圧について、放電電圧維持率で比較した結果を図３に併せて示す。 (Comparative Example 1)
A comparative example 1 active material was prepared in the same manner as in Example 1 except that no zirconium oxide was added. Similarly, a coin-type lithium secondary battery was prepared, and the initial charge capacity, the initial charge / discharge efficiency, the discharge capacity retention ratio, and the impedance were measured. The results are also shown in Table 1 and FIG. Moreover, the result of having compared by the discharge voltage maintenance factor about the average discharge voltage for every cycle is combined with FIG. 3, and is shown.

（比較例２）
酸化ジルコニウムとして比表面積が１２ｍ２／ｇのものを用いたことを除き、実施例１と同様にして比較例２活物質を作製した。同様にコイン型リチウム二次電池を作製し、初回充電容量・初回充放電効率及び放電容量維持率、インピーダンス測定を実施した。その結果を、表１、図１に併せて示す。 (Comparative Example 2)
Comparative Example 2 active material was prepared in the same manner as Example 1 except that zirconium oxide having a specific surface area of 12 m 2 / g was used. Similarly, a coin-type lithium secondary battery was prepared, and the initial charge capacity, the initial charge / discharge efficiency, the discharge capacity retention ratio, and the impedance were measured. The results are also shown in Table 1 and FIG.

（比較例３）
酸化ジルコニウムとして比表面積が１２０ｍ２／ｇのものを用いたことを除き、実施例１と同様にして比較例３活物質を作製した。同様にコイン型リチウム二次電池を作製し、初回充電容量・初回充放電効率及び放電容量維持率、インピーダンス測定を実施した。その結果を、表１、図１に併せて示す。 (Comparative Example 3)
Comparative Example 3 active material was prepared in the same manner as in Example 1 except that zirconium oxide having a specific surface area of 120 m 2 / g was used. Similarly, a coin-type lithium secondary battery was prepared, and the initial charge capacity, the initial charge / discharge efficiency, the discharge capacity retention ratio, and the impedance were measured. The results are also shown in Table 1 and FIG.

（比較例４）
酸化ジルコニウムの添加量を０．０５質量％にしたことを除き、実施例１と同様にして比較例３活物質を作製した。同様にコイン型リチウム二次電池を作製し、初回充電容量・初回充放電効率及び放電容量維持率、インピーダンス測定を実施した。その結果を、表１、図１に併せて示す。 (Comparative Example 4)
A comparative example 3 active material was prepared in the same manner as in Example 1 except that the amount of zirconium oxide added was 0.05% by mass. Similarly, a coin-type lithium secondary battery was prepared, and the initial charge capacity, the initial charge / discharge efficiency, the discharge capacity retention ratio, and the impedance were measured. The results are also shown in Table 1 and FIG.

（比較例５）
酸化ジルコニウムの添加量を１．５質量％にしたことを除き、実施例１と同様にして比較例５活物質を作製した。同様にコイン型リチウム二次電池を作製し、初回充電容量・初回充放電効率及び放電容量維持率、インピーダンス測定を実施した。その結果を、表１、図１に併せて示す。 (Comparative Example 5)
A comparative example 5 active material was produced in the same manner as in Example 1 except that the amount of zirconium oxide added was 1.5% by mass. Similarly, a coin-type lithium secondary battery was prepared, and the initial charge capacity, the initial charge / discharge efficiency, the discharge capacity retention ratio, and the impedance were measured. The results are also shown in Table 1 and FIG.

（比較例６）
酸化ジルコニウムを添加しないことを除き、実施例８同様にして比較例６活物質を作製した。同様にコイン型リチウム二次電池を作製し、初回充電容量・初回充放電効率及び放電容量維持率、インピーダンス測定を実施した。その結果を、表１、図２に併せて示す。 (Comparative Example 6)
Comparative Example 6 active material was prepared in the same manner as Example 8 except that zirconium oxide was not added. Similarly, a coin-type lithium secondary battery was prepared, and the initial charge capacity, the initial charge / discharge efficiency, the discharge capacity retention ratio, and the impedance were measured. The results are shown in Table 1 and FIG.

（比較例７）
酸化ジルコニウムを添加しないことを除き、実施例９同様にして比較例７活物質を作製した。同様にコイン型リチウム二次電池を作製し、初回充電容量・初回充放電効率及び放電容量維持率、インピーダンス測定を実施した。その結果を、表１、図２に併せて示す。 (Comparative Example 7)
Comparative Example 7 active material was prepared in the same manner as Example 9 except that no zirconium oxide was added. Similarly, a coin-type lithium secondary battery was prepared, and the initial charge capacity, the initial charge / discharge efficiency, the discharge capacity retention ratio, and the impedance were measured. The results are shown in Table 1 and FIG.

Figure 2017043496
Figure 2017043496

表１及び図１、図２及び図３から、本件発明により、リチウム遷移金属複合酸化物の最大粒子径が５０μｍ以下になるように制限し、さらに、比表面積が３０〜９０ｍ２／ｇの酸化ジルコニウムを前記リチウム遷移金属複合酸化物の表面に付着させることにより、
（１）表１に示す１００サイクルの充放電繰り返し後の放電容量維持率が改善され、
（２）図１、２に示すコールコールプロットの２つある半円のうち、拡散移動抵抗の大きさを示す右側の半円が比較例に比べて小さくなっているため本発明の効果が確認出来る。
（３）また、図３に示す実施例の平均放電電圧が、比較例よりも高めで推移しており、放電電圧の低下が抑制できていることが確認できた。 From Table 1, FIG. 1, FIG. 2 and FIG. 3, according to the present invention, the maximum particle size of the lithium transition metal composite oxide is limited to 50 μm or less, and the specific surface area is 30 to 90 m 2 / g. By attaching zirconium to the surface of the lithium transition metal composite oxide,
(1) The discharge capacity maintenance rate after 100 cycles of charge / discharge repetition shown in Table 1 is improved,
(2) Of the two semicircles in the Cole-Cole plot shown in FIGS. 1 and 2, the right semicircle indicating the magnitude of the diffusion movement resistance is smaller than that of the comparative example, so the effect of the present invention is confirmed. I can do it.
(3) Moreover, it has confirmed that the average discharge voltage of the Example shown in FIG. 3 was changing higher than the comparative example, and has suppressed the fall of the discharge voltage.

Claims (4)

化学組成が一般式Ｌｉ１＋ｘＮｉｙＣｏｚＭｎ１−ｘ−ｙ−ｚ−ｗＭｗＯ２で表され、ここで、ＭはＡｌ，Ｍｇ，Ｗ及びＺｒから選ばれた１種又は２種以上の金属元素であり、ｘは−０．０５≦ｘ≦０．０５、ｙは０．３≦ｙ＜０．９、ｚは０．０５≦ｚ≦０．３５、ｗは０≦ｗ≦０．１の範囲をとるリチウム遷移金属複合酸化物に比表面積が３０〜９０ｍ２／ｇの酸化ジルコニウムが、前記リチウム遷移金属複合酸化物の粒子の表面に０．１〜１．０質量％付着した複合粒子からなる、最大粒子径が５０μｍ以下であることを特徴とするリチウム遷移金属複合酸化物。 The chemical composition is represented by the general formula Li 1 + x Ni y Co z Mn 1-xyzw M w O 2 , where M is one or two selected from Al, Mg, W and Zr X is −0.05 ≦ x ≦ 0.05, y is 0.3 ≦ y <0.9, z is 0.05 ≦ z ≦ 0.35, and w is 0 ≦ w ≦. Zirconium oxide having a specific surface area of 30 to 90 m 2 / g adheres to the surface of the lithium transition metal composite oxide particles in an amount of 0.1 to 1.0% by mass on the lithium transition metal composite oxide having a range of 0.1. A lithium transition metal composite oxide comprising a composite particle having a maximum particle size of 50 μm or less. リチウム塩及び遷移金属複合水酸化物と同時に、または順に比表面積が３０〜９０ｍ２／ｇの酸化ジルコニウムを乾式で混合し、ついで焼成温度が５００℃以上７００℃以下に保持される第一の焼成工程と、前記第一の焼成工程から焼成温度を下げずに引き続き行われ、焼成温度が７００℃以上１０００℃以下に保持される第二の焼成工程または前記第一の焼成工程から焼成温度を一旦室温まで下げた後、焼成温度が７００℃以上１０００℃以下に保持される第二の焼成工程により焼成することを特徴とする請求項一記載のリチウム遷移金属複合酸化物の製造方法。 A first firing in which zirconium oxide having a specific surface area of 30 to 90 m 2 / g is mixed in a dry process simultaneously with a lithium salt and a transition metal composite hydroxide, and then maintained at a firing temperature of 500 ° C. to 700 ° C. And a second baking step in which the baking temperature is maintained at 700 ° C. or more and 1000 ° C. or less, or the baking temperature is temporarily changed from the first baking step. The method for producing a lithium transition metal composite oxide according to claim 1, wherein after the temperature is lowered to room temperature, firing is performed in a second firing step in which the firing temperature is maintained at 700 ° C or higher and 1000 ° C or lower. 請求項２に記載のリチウム塩及び遷移金属複合水酸化物と混合する酸化ジルコニウムの添加量がリチウム遷移金属複合酸化物の０．１〜１．０質量％であることを特徴とする請求項２に記載のリチウム遷移金属複合酸化物の製造方法。 The addition amount of zirconium oxide mixed with the lithium salt and the transition metal composite hydroxide according to claim 2 is 0.1 to 1.0 mass% of the lithium transition metal composite oxide. A process for producing a lithium transition metal composite oxide as described in 1 above. 前記一般式Ｌｉ１＋ｘＮｉｙＣｏｚＭｎ１−ｘ−ｙ−ｚ−ｗＭｗＯ２で表されるリチウム遷移金属複合酸化物となるように、リチウム塩及び遷移金属複合化合物を混合し、ここで同時に、または順に比表面積が３０〜９０ｍ２／ｇの酸化ジルコニウム粒子を混合して、混合粉を焼成させることにより前記リチウム遷移金属複合酸化物の表面に酸化ジルコニウムが付着した複合粒子にすることを特徴とする請求項２または３に記載のリチウム遷移金属複合酸化物の製造方法。 A lithium salt and a transition metal composite compound are mixed so as to be a lithium transition metal composite oxide represented by the general formula Li 1 + x Ni y Co z Mn 1-xy-z-w M w O 2 , At the same time or sequentially, zirconium oxide particles having a specific surface area of 30 to 90 m 2 / g are mixed, and the mixed powder is fired to obtain composite particles in which zirconium oxide is adhered to the surface of the lithium transition metal composite oxide. The method for producing a lithium transition metal composite oxide according to claim 2 or 3.
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