JP2005347211A - Manufacturing method of lithium compound oxide for lithium secondary battery cathode - Google Patents
Manufacturing method of lithium compound oxide for lithium secondary battery cathode Download PDFInfo
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Abstract
Description
本発明は、体積容量密度が大きく、安全性が高く、充放電サイクル耐久性、及び低温特性に優れた、リチウム二次電池正極用のリチウム含有複合酸化物の製造方法、製造されたリチウム含有複合酸化物を含むリチウム二次電池用正極、及びリチウム二次電池に関する。 The present invention provides a method for producing a lithium-containing composite oxide for a positive electrode of a lithium secondary battery, which has a large volumetric capacity density, high safety, excellent charge / discharge cycle durability, and low-temperature characteristics, and a lithium-containing composite produced The present invention relates to a positive electrode for a lithium secondary battery including an oxide and a lithium secondary battery.
近年、機器のポータブル化、コードレス化が進むにつれ、小型、軽量でかつ高エネルギー密度を有するリチウム二次電池などの非水電解液二次電池に対する要求がますます高まっている。かかる非水電解液二次電池用の正極活物質には、ＬｉＣｏＯ2、ＬｉＮｉＯ2、ＬｉＮｉ0.8Ｃｏ0.2Ｏ2、ＬｉＭｎ2Ｏ4、ＬｉＭｎＯ2などのリチウムと遷移金属の複合酸化物が知られている。 In recent years, as devices become more portable and cordless, demands for non-aqueous electrolyte secondary batteries such as lithium secondary batteries that are small, lightweight, and have high energy density are increasing. As such positive electrode active materials for non-aqueous electrolyte secondary batteries, composite oxides of lithium and transition metals such as LiCoO 2 , LiNiO 2 , LiNi 0.8 Co 0.2 O 2 , LiMn 2 O 4 , LiMnO 2 are known. Yes.
なかでも、リチウム含有複合酸化物（ＬｉＣｏＯ2）を正極活物質として用い、リチウム合金、グラファイト、カーボンファイバーなどのカーボンを負極として用いたリチウム二次電池は、４Ｖ級の高い電圧が得られるため、高エネルギー密度を有する電池として広く使用されている。 Among them, a lithium secondary battery using lithium-containing composite oxide (LiCoO 2 ) as a positive electrode active material and using carbon such as lithium alloy, graphite, or carbon fiber as a negative electrode can obtain a high voltage of 4V, It is widely used as a battery having a high energy density.
しかしながら、ＬｉＣｏＯ2を正極活物質として用いた非水系二次電池の場合、正極電極層の単位体積当たりの容量密度及び安全性の更なる向上が望まれるとともに、充放電サイクルを繰り返し行うことにより、その電池放電容量が徐々に減少するというサイクル特性の劣化、重量容量密度の問題、あるいは低温での放電容量低下が大きいという問題などがあった。 However, in the case of a non-aqueous secondary battery using LiCoO 2 as a positive electrode active material, further improvement in capacity density per unit volume and safety of the positive electrode layer is desired, and by repeatedly performing a charge / discharge cycle, There have been problems such as deterioration in cycle characteristics in which the battery discharge capacity gradually decreases, problems in weight capacity density, and large reductions in discharge capacity at low temperatures.
これらの問題の一部を解決するために、特許文献１には、正極活物質であるＬｉＣｏＯ2の平均粒径を３〜９μｍ、及び粒径３〜１５μｍの粒子群の占める体積を全体積の７５％以上とし、かつＣｕＫαを線源とするＸ線回折によって測定される２θ＝約１９°と２θ＝４５°との回折ピーク強度比を特定値とすることにより、塗布特性、自己放電特性、サイクル性に優れた活物質とすることが提案されている。更に、該公報には、ＬｉＣｏＯ2の粒径が１μｍ以下又は２５μｍ以上の粒径分布を実質的に有さないものが好ましい態様として提案されている。しかし、かかる正極活物質では、塗布特性ならびにサイクル特性は向上するものの、安全性、体積容量密度、重量容量密度を充分に満足するものは得られていない。 In order to solve some of these problems, Patent Document 1 discloses that the average particle size of LiCoO 2 that is a positive electrode active material is 3 to 9 μm, and the volume occupied by a particle group having a particle size of 3 to 15 μm is the total volume. By setting the diffraction peak intensity ratio between 2θ = about 19 ° and 2θ = 45 ° measured by X-ray diffraction using CuKα as a radiation source to a specific value, the coating characteristics, self-discharge characteristics, It has been proposed to make an active material excellent in cycle performance. Further, the publication proposes a preferred embodiment in which the particle size of LiCoO 2 does not substantially have a particle size distribution of 1 μm or less or 25 μm or more. However, such a positive electrode active material has improved coating characteristics and cycle characteristics, but has not been sufficiently satisfactory in safety, volume capacity density, and weight capacity density.
また、電池特性に関する課題を解決するために、特許文献２にＣｏ原子の５〜３５％をＷ、Ｍｎ、Ｔａ、Ｔｉ又はＮｂで置換することがサイクル特性改良のために提案されている。また、特許文献３には、格子定数のｃ軸長が１４．０５１Å以下であり、結晶子の（１１０）方向の結晶子径が４５〜１００ｎｍである、六方晶系のＬｉＣｏＯ2を正極活物質とすることによりサイクル特性を向上させることが提案されている。 Moreover, in order to solve the problem regarding battery characteristics, Patent Document 2 proposes to replace 5 to 35% of Co atoms with W, Mn, Ta, Ti, or Nb in order to improve cycle characteristics. In Patent Document 3, hexagonal LiCoO 2 having a c-axis length of a lattice constant of not more than 14.051 mm and a crystallite diameter in the (110) direction of 45 to 100 nm is used as a positive electrode active material. It has been proposed to improve cycle characteristics.
更に、特許文献４には、式ＬｉxＮｉ1-ｍＮｍＯ2（式中、０＜ｘ＜１．１、０≦ｍ≦１である。）を有し、一次粒子が板状ないし柱状であり、かつ（体積基準累積９５％径−体積基準累積５％径）／体積基準累積５％径が３以下で、平均粒径が１〜５０μｍを有するリチウム複合酸化物が、重量あたりの初期放電容量が高く、また充放電サイクル耐久性に優れることが提案されている。 Further, Patent Document 4 has the formula Li x Ni 1-m N m O 2 (where 0 <x <1.1, 0 ≦ m ≦ 1), and the primary particles are plate-like or Lithium composite oxide having a columnar shape and (volume-based cumulative 95% diameter−volume-based cumulative 5% diameter) / volume-based cumulative 5% diameter of 3 or less and an average particle diameter of 1 to 50 μm is It has been proposed that the initial discharge capacity is high and the charge / discharge cycle durability is excellent.
また、特許文献５には、平均粒子径０．０１〜２μｍを有する、コバルト水酸化物やコバルトオキシ水酸化物やコバルト酸化物の一次粒子を凝集させて平均粒子径０．５〜３０μｍの二次粒子を形成したコバルト化合物粉末をリチウム化することが提案されている。しかし、この場合にも高い体積容量密度の正極物質は得られず、また、サイクル特性、安全性や大電流放電特性の点でもなお充分ではない。 In Patent Document 5, primary particles having an average particle diameter of 0.01 to 2 μm and agglomeration of primary particles of cobalt hydroxide, cobalt oxyhydroxide, and cobalt oxide are aggregated. It has been proposed to lithiate cobalt compound powders that have formed secondary particles. However, even in this case, a positive electrode material having a high volume capacity density cannot be obtained, and the cycle characteristics, safety, and large current discharge characteristics are still insufficient.
上記のように、上記従来の技術では、リチウム複合酸化物を正極活物質に用いたリチウム二次電池において、体積容量密度、安全性、塗工均一性、サイクル特性更には低温特性などの全てを充分に満足するものは未だ得られていない。
本発明は、体積容量密度が大きく、安全性が高く、充放電サイクル耐久性に優れ、更には、低温特性に優れた、リチウム二次電池正極用のリチウムコバルト複合酸化物などのリチウム含有複合酸化物の製造方法、製造されたリチウム含有複合酸化物を含む、リチウム二次電池用正極、及びリチウム二次電池の提供を目的とする。 The present invention is a lithium-containing composite oxide such as a lithium cobalt composite oxide for a lithium secondary battery positive electrode, which has a large volumetric capacity density, high safety, excellent charge / discharge cycle durability, and excellent low temperature characteristics. It aims at providing the manufacturing method of a thing, the positive electrode for lithium secondary batteries containing the manufactured lithium containing complex oxide, and a lithium secondary battery.
本発明者は、鋭意研究を続けたところ、以下の知見を通じて本発明に到達した。即ち、コバルト酸リチウムなどのリチウム含有複合酸化物は基本的には、体積容量密度に優れた特性を有するが、充放電時のリチウムの出入りに伴い結晶構造が六方晶と単斜晶との相転移し、膨張と収縮を繰り返すため、結晶構造の破壊が生じサイクル特性が劣化するという問題がある。この問題は、従来、上記のように、コバルト酸リチウムのコバルトの一部をＷ、Ｍｎ、Ｔａ、Ｔｉ又はＮｂなどの他の元素（以下これらの元素を置換元素ともいう）で置換し、結晶構造の安定化を通じて解決することが図られている。 As a result of intensive research, the present inventor has reached the present invention through the following findings. In other words, lithium-containing composite oxides such as lithium cobaltate basically have excellent volume capacity density, but the crystal structure becomes a phase between hexagonal and monoclinic as lithium enters and exits during charge and discharge. Since the transition and the expansion and contraction are repeated, there is a problem that the crystal structure is destroyed and the cycle characteristics are deteriorated. Conventionally, as described above, a part of cobalt of lithium cobalt oxide is replaced with another element such as W, Mn, Ta, Ti, or Nb (hereinafter, these elements are also referred to as substitution elements), It is attempted to solve the problem by stabilizing the structure.
しかし、上記した従来法による場合には、後記する例（比較例）３、４、６及び８に示されるように必ずしも狙いどおりの結果は得られていない。本発明者は、一般式ＬipＮxＭyＬｚＯｑＦa（但し、Ｎは、Ｃｏ、Ｍｎ及びＮｉからなる群から選ばれる少なくとも１種の元素であり、Ｍはアルミニウムまたは遷移金属元素であり、Ｌは、リン、ホウ素、ケイ素及びアルカリ土類金属元素からなる群から選ばれる少なくとも１種である。０．９≦ｐ≦１．１、０．９７≦ｘ＜１．００、０＜ｙ≦０．０３、０＜ｚ≦０．０３、１．９≦ｑ≦２．１、ｘ＋ｙ+ｚ＝１、０≦ａ≦０．０２）で表されるリチウム含有複合酸化物を製造する場合において、上記Ｍ元素及びＬ元素の原料化合物として、分子内にＭ元素とＬ元素とが酸素を介して結合する、Ｍ−Ｏ−Ｌ構造を有しかつ酸素数が５以上を有する特定の有機金属化合物を選択し、該有機金属化合物を有機溶媒溶液の形態にて使用することにより上記の課題を達成し得ることを見出した。 However, in the case of the above-described conventional method, as shown in examples (comparative examples) 3, 4, 6, and 8 to be described later, the intended result is not necessarily obtained. The present inventor has general formula Li p N x M y L z O q F a ( where, N is the, Co, at least one element selected from the group consisting of Mn and Ni, M is aluminum or a transition metal L is at least one selected from the group consisting of phosphorus, boron, silicon and alkaline earth metal elements, 0.9 ≦ p ≦ 1.1, 0.97 ≦ x <1.00, 0 <y ≦ 0.03, 0 <z ≦ 0.03, 1.9 ≦ q ≦ 2.1, x + y + z = 1, 0 ≦ a ≦ 0.02) In the case of manufacturing, as a raw material compound of the above M element and L element, it has an M-O-L structure in which M element and L element are bonded through oxygen in the molecule, and has an oxygen number of 5 or more A specific organometallic compound is selected and used in the form of an organic solvent solution. It found that can achieve the above-mentioned problems by.
すなわち、本発明による場合、体積容量密度が大きく、安全性が高く、充放電サイクル耐久性に優れ、低温特性に優れた、リチウム二次電池正極用のリチウム含有複合酸化物が得られる。これは、リチウム含有複合酸化物におけるコバルトなどの被置換元素（Ｎ元素）は、置換元素であるＭ元素及びＬ元素により、極めて充分にかつ均一に置換されることにより達成されるものと思われる。 That is, according to the present invention, a lithium-containing composite oxide for a lithium secondary battery positive electrode having a large volumetric capacity density, high safety, excellent charge / discharge cycle durability, and excellent low temperature characteristics can be obtained. This is considered to be achieved when the element to be substituted (N element) such as cobalt in the lithium-containing composite oxide is very sufficiently and uniformly substituted by the M element and L element which are substitution elements. .
かくして、本発明は以下の構成を要旨とするものである。
（１）リチウム原料化合物、Ｎ元素原料化合物、Ｍ元素原料化合物、Ｌ元素原料化合物、及び必要に応じて含まれるフッ素原料化合物の混合物を酸素含有雰囲気で焼成する、一般式ＬipＮxＭyＬｚＯｑＦa（但し、Ｎは、Ｃｏ、Ｍｎ及びＮｉからなる群から選ばれる少なくとも１種の元素であり、Ｍはアルミニウムまたは遷移金属元素であり、Ｌは、リン、ホウ素、ケイ素及びアルカリ土類金属元素からなる群から選ばれる少なくとも１種である。０．９≦ｐ≦１．１、０．９７≦ｘ＜１．００、０＜ｙ≦０．０３、０＜ｚ≦０．０３、１．９≦ｑ≦２．１、ｘ＋ｙ+ｚ＝１、０≦ａ≦０．０２）で表されるリチウム含有複合酸化物の製造方法であって、Ｍ元素及びＬ元素の原料化合物として、分子内にＭ元素とＬ元素とが酸素を介して結合する、Ｍ−Ｏ−Ｌ構造を有しかつ酸素数が５以上を有する有機金属化合物を選択し、該有機金属化合物を有機溶媒溶液の形態にて使用し、上記混合物の焼成前に上記有機溶媒を除去することを特徴とするリチウム二次電池正極用リチウム含有複合酸化物の製造方法。
（２）リチウム原料化合物、Ｎ元素原料化合物及び必要に応じてフッ素原料化合物と、前記有機金属化合物の有機溶媒溶液とを混合した後、得られる混合物から溶媒を除去し、焼成する上記（１）に記載の製造方法。
（３）Ｎ元素原料化合物及び必要に応じてフッ素原料化合物と、前記有機金属化合物の有機溶媒溶液とを混合し、得られる混合物から溶媒を除去した後、次いでリチウム原料化合物を混合し、焼成する上記（１）に記載の製造方法。
（４）リチウム原料化合物、Ｎ元素原料化合物、及び必要に応じてフッ素原料化合物の混合物を酸素含有雰囲気で焼成して得られるリチウム複合酸化物と、前記有機金属化合物の有機溶媒溶液とを混合し、得られる混合物から溶媒を除去し、焼成する上記（１）に記載の製造方法。
（５）前記有機金属化合物の有機溶媒溶液が５容量％以下の水分を含有する上記（１）〜（４）のいずれかに記載の製造方法。
（６）前記有機金属化合物が、（２−エチルヘキサノネート）−Ｍｇ−Ｏ−Ａｌ−（２−エチルヘキサノネート）（ｓｅｃ−ブトキサイド）である上記（１）〜（５）のいずれかに記載の製造方法。
（７）前記有機金属化合物が、（ネオデカノエイト）Ｚｒ（＝Ｏ）−Ｏ−Ｐ（＝Ｏ）（ブトキサイド）２である上記（１）〜（５）のいずれかに記載の製造方法。
（８）Ｍ元素が、Ｔｉ、Ｚｒ、Ｈｆ、Ｎｂ、Ｔａ、Ｃｕ、Ｚｎ、及びＡｌからなる群から選ばれる少なくとも１種である上記（１）〜（７）のいずれかに記載の製造方法。
（９）Ｍ元素がＡｌであり、かつＬ元素がＭｇであり、Ａｌ／Ｍｇが原子比で１／３〜３／１であり、かつ０．００５≦ｙ≦０．０２５である上記（１）〜（７）のいずれかに記載の製造方法。
（１０）Ｌ元素がＭｇであり、Ｍ元素がＴｉ、Ｚｒ、Ｈｆ、Ｔａ、及びＮｂからなる群から選ばれる少なくとも１種の元素であり、Ｍ／Ｍｇが原子比で１／４０〜２／１であり、かつ０．００５≦ｙ≦０．０２５である上記（１）〜（７）のいずれかに記載の製造方法。
（１１）リチウム含有複合酸化物の、ＣｕＫαを線源とするＸ線回折によって測定される、２θ＝６６〜６７°の（１１０）面の回折ピークの積分幅が０．０８〜４０、表面積が０．３〜０．７ｍ2／ｇ、発熱開始温度が１６０℃以上である上記（１）〜（１０）のいずれかに記載の製造方法。
（１２）上記（１）〜（１１）のいずれかに記載の製造方法により製造されたリチウム含有複合酸化物を含むリチウム二次電池用正極。
（１３）上記（１２）に記載された正極を使用したリチウム二次電池。
Thus, the gist of the present invention is as follows.
(1) lithium source compound, N element source compounds, M element source compounds, L element source compounds, and the mixture is fired in an oxygen-containing atmosphere of the fluorine raw material compounds contained as required, general formula Li p N x M y L z O q Fa (where N is at least one element selected from the group consisting of Co, Mn and Ni, M is aluminum or a transition metal element, L is phosphorus, boron, silicon and At least one selected from the group consisting of alkaline earth metal elements: 0.9 ≦ p ≦ 1.1, 0.97 ≦ x <1.00, 0 <y ≦ 0.03, 0 <z ≦ 0. .03, 1.9 ≦ q ≦ 2.1, x + y + z = 1, 0 ≦ a ≦ 0.02), which is a raw material of M element and L element As a compound, M element and L element in the molecule through oxygen An organic metal compound having an M-O-L structure and an oxygen number of 5 or more is selected, the organic metal compound is used in the form of an organic solvent solution, and the organic compound is baked before the mixture is baked. The manufacturing method of the lithium containing complex oxide for lithium secondary battery positive electrodes characterized by removing a solvent.
(2) The lithium raw material compound, the N element raw material compound and, if necessary, the fluorine raw material compound and an organic solvent solution of the organometallic compound are mixed, and then the solvent is removed from the resulting mixture, followed by firing (1) The manufacturing method as described in.
(3) The N element raw material compound and, if necessary, the fluorine raw material compound and the organic solvent solution of the organometallic compound are mixed, and after removing the solvent from the resulting mixture, the lithium raw material compound is then mixed and fired. The manufacturing method as described in said (1).
(4) A lithium composite oxide obtained by firing a mixture of a lithium raw material compound, an N element raw material compound and, if necessary, a fluorine raw material compound in an oxygen-containing atmosphere and an organic solvent solution of the organometallic compound are mixed. The production method according to (1) above, wherein the solvent is removed from the obtained mixture and the mixture is fired.
(5) The manufacturing method in any one of said (1)-(4) in which the organic-solvent solution of the said organometallic compound contains the water | moisture content of 5 volume% or less.
(6) Any of the above (1) to (5), wherein the organometallic compound is (2-ethylhexanonate) -Mg-O-Al- (2-ethylhexanonate) (sec-butoxide) The manufacturing method as described in.
(7) The manufacturing method in any one of said (1)-(5) whose said organometallic compound is (neodecanoate) Zr (= O) -OP (= O) (butoxide) 2.
(8) The manufacturing method according to any one of (1) to (7), wherein the M element is at least one selected from the group consisting of Ti, Zr, Hf, Nb, Ta, Cu, Zn, and Al. .
(9) The above (1) where M element is Al, L element is Mg, Al / Mg is 1/3 to 3/1 in atomic ratio, and 0.005 ≦ y ≦ 0.025 ) To (7).
(10) The L element is Mg, the M element is at least one element selected from the group consisting of Ti, Zr, Hf, Ta, and Nb, and M / Mg is in an atomic ratio of 1/40 to 2 / 1 and the production method according to any one of the above (1) to (7), wherein 0.005 ≦ y ≦ 0.025.
(11) The integrated width of the diffraction peak of the (110) plane of 2θ = 66 to 67 ° measured by X-ray diffraction using CuKα as the radiation source of the lithium-containing composite oxide is 0.08 to 40, and the surface area is The production method according to any one of (1) to (10), wherein 0.3 to 0.7 m 2 / g and the heat generation start temperature is 160 ° C. or higher.
(12) A positive electrode for a lithium secondary battery comprising a lithium-containing composite oxide produced by the production method according to any one of (1) to (11) above.
(13) A lithium secondary battery using the positive electrode described in (12) above.
本発明によれば、体積容量密度が大きく、安全性が高く、充放電サイクル耐久性に優れ、更には、低温特性に優れた、リチウム二次電池正極用リチウムコバルト複合酸化物などのリチウム含有複合酸化物の製造方法、製造されたリチウム含有複合酸化物を含む、リチウム二次電池用正極、及びリチウム二次電池が提供される。 According to the present invention, a lithium-containing composite such as a lithium-cobalt composite oxide for a lithium secondary battery positive electrode having a large volumetric capacity density, high safety, excellent charge / discharge cycle durability, and excellent low-temperature characteristics. Provided are a method for producing an oxide, a positive electrode for a lithium secondary battery including the produced lithium-containing composite oxide, and a lithium secondary battery.
本発明で製造されるリチウム二次電池正極用のリチウム含有複合酸化物は、一般式ＬipＮxＭyＬｚＯｑＦaで表される。かかる一般式における、ｐ、ｘ、ｙ、ｚ、ｑ及びａは上記に定義される。なかでも、ｐ、ｘ、ｙ、ｚ、ｑ及びａは下記が好ましい。０．９７≦ｐ≦１．０３、０．９９≦ｘ＜１．００、０．０００５≦ｙ≦０．０２５、０＜ｚ≦０．０１、１．９５≦ｑ≦２．０５、ｘ＋ｙ+ｚ＝１、０．００１≦ａ≦０．０１。ここで、ａが０より大きいときには、酸素原子の一部がフッ素原子で置換された複合酸化物になるが、この場合には、得られた正極活物質の安全性が向上する。 Lithium-containing composite oxide for a lithium secondary battery positive electrode produced in the present invention is represented by the general formula Li p N x M y L z O q F a. In this general formula, p, x, y, z, q and a are defined above. Among these, p, x, y, z, q and a are preferably as follows. 0.97 ≦ p ≦ 1.03, 0.99 ≦ x <1.00, 0.0005 ≦ y ≦ 0.025, 0 <z ≦ 0.01, 1.95 ≦ q ≦ 2.05, x + y + z = 1, 0.001 ≦ a ≦ 0.01. Here, when a is larger than 0, a composite oxide in which some of the oxygen atoms are substituted with fluorine atoms is obtained. In this case, the safety of the obtained positive electrode active material is improved.
Ｎ元素は、Ｃｏ、Ｍｎ及びＮｉからなる群から選ばれる少なくとも１種の元素であり、なかでも、Ｃｏ、Ｎｉ、ＣｏとＮｉ、ＭｎとＮｉ、ＣｏとＮｉとＭｎである場合が好ましい。Ｍ元素は、Ｎ元素以外の遷移金属元素、アルミニウムからなる群から選ばれる少なくとも１種の元素である。ここで、遷移金属元素は周期表の４族、５族、６族、７族、８族、９族、１０族及び１１族の遷移金属を表す。なかでも、Ｍ元素は、Ｔｉ、Ｚｒ、Ｈｆ、Ｎｂ、Ｔａ、Ｃｕ、Ｚｎ及びＡｌからなる群から選ばれる少なくとも１つの元素が好ましい。特に、容量発現性、安全性、サイクル耐久性などの見地より、Ｔｉ、Ｚｒ、Ｈｆ又はＡｌが好ましい。Ｌ元素は、リン、ホウ素、ケイ素又はアルカリ土類金属元素からなる群から選ばれる少なくとも１種の元素である。中でもＬ元素はＰ、Ｂ、Ｍｇ、Ｃａ、Ｓｒからなる群から選ばれる少なくとも１種の元素が好ましい。特にＰ、Ｂ、Ｍｇが好ましい。 The N element is at least one element selected from the group consisting of Co, Mn and Ni, and among them, Co, Ni, Co and Ni, Mn and Ni, and Co, Ni and Mn are preferable. The M element is at least one element selected from the group consisting of transition metal elements other than the N element and aluminum. Here, the transition metal element represents a transition metal of Group 4, Group 5, Group 6, Group 7, Group 8, Group 9, Group 10, Group 11 of the periodic table. Among these, the M element is preferably at least one element selected from the group consisting of Ti, Zr, Hf, Nb, Ta, Cu, Zn, and Al. In particular, Ti, Zr, Hf, or Al is preferable from the viewpoint of capacity development, safety, cycle durability, and the like. The L element is at least one element selected from the group consisting of phosphorus, boron, silicon, or alkaline earth metal elements. Among these, the L element is preferably at least one element selected from the group consisting of P, B, Mg, Ca, and Sr. P, B, and Mg are particularly preferable.
本発明において、特に、Ｍ元素がＡｌであり、Ｌ元素がＭｇからなり、ＡｌとＭｇが原子比で好ましくは１／３〜３／１、特に好ましくは２／３〜３／２であり、かつｙが好ましくは、０．００５≦ｙ≦０．０２５、特に好ましくは０．０１≦ｙ≦０．０２である場合には、電池性能のバランス、即ち、初期重量容量密度、安全性、充放電サイクル安定性のバランスが良いので特に好ましい。 In the present invention, in particular, the M element is Al, the L element is Mg, and Al and Mg are preferably in an atomic ratio of 1/3 to 3/1, particularly preferably 2/3 to 3/2, And when y is preferably 0.005 ≦ y ≦ 0.025, particularly preferably 0.01 ≦ y ≦ 0.02, the balance of battery performance, that is, initial weight capacity density, safety, This is particularly preferable because the discharge cycle stability is well balanced.
また、本発明において、Ｌ元素がＭｇであり、Ｍ元素がＴｉ、Ｚｒ、Ｔａ、及びＮｂからなる群から選ばれる少なくとも１種の元素であり、ＭとＭｇが原子比で好ましくは１／４０〜２／１、特に好ましくは１／３０〜１／５であり、かつｙが好ましくは０．００５≦ｙ≦０．０２５、特に好ましくは０．０１≦ｙ≦０．０２である場合には、電池性能のバランス、即ち、初期重量容量密度、初期体積容量密度、安全性、充放電サイクル安定性のバランスが良いので特に好ましい。 In the present invention, the L element is Mg, the M element is at least one element selected from the group consisting of Ti, Zr, Ta, and Nb, and M and Mg are preferably in an atomic ratio of 1/40. To 2/1, particularly preferably 1/30 to 1/5, and y is preferably 0.005 ≦ y ≦ 0.025, particularly preferably 0.01 ≦ y ≦ 0.02. This is particularly preferable because the battery performance balance, that is, the initial weight capacity density, initial volume capacity density, safety, and charge / discharge cycle stability is well balanced.
本発明において、上記Ｍ元素、Ｌ元素及び／又はフッ素を含有せしめる場合は、Ｍ元素、Ｌ元素及びフッ素は、いずれもリチウム含有複合酸化物粒子の表面に存在していることが好ましい。これらの元素が表面に存在することにより、少量の添加で電池性能の低下を招来することなく、安全性、充放電サイクル特性等の重要な電池特性を改良できる。これらの元素が表面に存在するか否かは正極粒子について、分光分析、例えば、ＸＰＳ分析を行うことにより判断できる。 In the present invention, when the M element, L element and / or fluorine are contained, it is preferable that the M element, L element and fluorine are all present on the surface of the lithium-containing composite oxide particle. The presence of these elements on the surface can improve important battery characteristics such as safety and charge / discharge cycle characteristics without causing a decrease in battery performance when added in a small amount. Whether or not these elements are present on the surface can be determined by performing spectroscopic analysis, for example, XPS analysis, on the positive electrode particles.
本発明のリチウム含有複合酸化物を製造する場合、リチウム原料化合物、Ｎ元素原料化合物、Ｍ元素原料化合物、Ｌ元素原料化合物、及び必要に応じて含まれるフッ素原料化合物の混合物を酸素含有雰囲気で焼成することにより製造される。本発明では、Ｍ元素及びＬ元素の原料化合物として、分子内にＭ元素とＬ元素とが酸素を介して結合する、Ｍ−Ｏ−Ｌ構造を有しかつ酸素数が５以上、好ましくは５〜１０を有する有機金属化合物を選択し使用される。これらの有機金属化合物は有機溶媒に対する溶解性が大きく、高濃度の有機溶媒溶液が得られる。 When the lithium-containing composite oxide of the present invention is produced, a mixture of a lithium raw material compound, an N element raw material compound, an M element raw material compound, an L element raw material compound, and an optionally contained fluorine raw material compound is fired in an oxygen-containing atmosphere. It is manufactured by doing. In the present invention, as a raw material compound of M element and L element, it has an M-OL structure in which M element and L element are bonded via oxygen in the molecule, and the number of oxygen is 5 or more, preferably 5 Is selected and used. These organometallic compounds are highly soluble in organic solvents, and high-concentration organic solvent solutions can be obtained.
本発明で使用される上記有機金属化合物として、該構造を有する種々の有機塩、有機酸金属塩、有機酸エステル、有機金属キレート錯体化合物が使用でき、また、金属アルコキシドをキレート等で安定化した化合物であってもよい。具体的には、２−エチルヘキサネート、ネオデカネート、エチルアセチルアセトネート、アセチルアセトネート、イソプロポキサイド、ブトキサイドなどが挙げられる。なかでも、（２−エチルヘキサノネート）−Ｍｇ−Ｏ−Ａｌ−（２−エチルヘキサノネート）（ｓｅｃ−ブトキサイド）、（ネオデカノエイト）Ｚｒ（＝Ｏ）−Ｏ−Ｐ（＝Ｏ）（ブトキサイド）2などが挙げられる。 As the organometallic compound used in the present invention, various organic salts, organic acid metal salts, organic acid esters and organometallic chelate complex compounds having the structure can be used, and the metal alkoxide is stabilized with a chelate or the like. It may be a compound. Specific examples include 2-ethylhexanate, neodecanate, ethyl acetylacetonate, acetylacetonate, isopropoxide, butoxide, and the like. Among them, (2-ethylhexanoate) -Mg-O-Al- (2-ethylhexanoate) (sec-butoxide), (neodecanoate) Zr (= O) -OP (= O) (butoxide) 2 ).
上記有機金属化合物を溶解する有機溶媒としては、トルエン、キシレンなどの芳香族炭化水素類、エタノール、イソプロピルアルコール、ブタノールなどのアルコール類、ブタン、ヘキサンなどの脂肪属炭化水素類が使用される。なかでも金属化合物の安定性の理由からアルコール類の使用が好ましい。有機溶媒中の有機金属化合物の濃度は、後の工程で乾燥により溶媒を除去する必要がある点から高濃度の方が好ましい。しかし、高濃度過ぎると粘度が高くなり、正極活物質を形成する他の元素含有化合物粉末との均一混合性が低下するので、好ましくは１〜３０質量％、特には４〜２０質量％が好ましい。 As the organic solvent for dissolving the organometallic compound, aromatic hydrocarbons such as toluene and xylene, alcohols such as ethanol, isopropyl alcohol and butanol, and aliphatic hydrocarbons such as butane and hexane are used. Of these, the use of alcohols is preferred because of the stability of the metal compound. The concentration of the organometallic compound in the organic solvent is preferably higher since it is necessary to remove the solvent by drying in a later step. However, if the concentration is too high, the viscosity increases, and the uniform mixing with other element-containing compound powders forming the positive electrode active material decreases, so 1-30% by mass, particularly 4-20% by mass is preferable. .
なお、有機金属化合物の有機溶媒溶液を形成する場合において、本発明では、有機溶媒ともに水分を含有させることもできる。水分を含有させた場合、金属化合物が加水分解され易くなるので、該水分の含有量は、有機溶媒溶液中、好ましくは５．０容量％以下、特には１．０容量％以下であるのが好適である。 In addition, when forming the organic solvent solution of an organometallic compound, in this invention, a water | moisture content can also be included with an organic solvent. When water is contained, the metal compound is easily hydrolyzed, so that the water content is preferably 5.0% by volume or less, particularly 1.0% by volume or less in the organic solvent solution. Is preferred.
本発明のリチウム含有複合酸化物を製造する場合の他の原料である、Ｎ元素原料化合物としては、Ｎがコバルトの場合には、炭酸コバルト、水酸化コバルトあるいはオキシ水酸化コバルト、酸化コバルトが好ましく使用される。特に水酸化コバルトあるいはオキシ水酸化コバルトが性能が発現しやすいので好ましい。また、Ｎがニッケルの場合には、水酸化ニッケル、炭酸ニッケルが好ましく使用される。また、Ｎがマンガンの場合には、炭酸マンガンが好ましく使用される。 As the N element raw material compound, which is another raw material when producing the lithium-containing composite oxide of the present invention, when N is cobalt, cobalt carbonate, cobalt hydroxide, cobalt oxyhydroxide, or cobalt oxide is preferable. used. In particular, cobalt hydroxide or cobalt oxyhydroxide is preferable because performance is easily exhibited. When N is nickel, nickel hydroxide and nickel carbonate are preferably used. When N is manganese, manganese carbonate is preferably used.
また、Ｎ元素がニッケルとコバルトを含む化合物の場合は、Ｎｉ０．８Ｃｏ０．２ＯＯＨ、Ｎｉ０．８Ｃｏ０．２（ＯＨ）２などが、Ｎ元素がニッケルとマンガンを含む化合物の場合はＮｉ０．５Ｍｎ０．５ＯＯＨなどが、Ｎ元素がニッケルとコバルトとマンガンを含む化合物の場合はＮｉ０．４Ｃｏ０．２Ｍｎ０．４（ＯＨ）２、Ｎｉ１／３Ｃｏ１／３Ｍｎ１／３ＯＯＨなどがそれぞれ好ましく例示される。 In the case where the N element is a compound containing nickel and cobalt, Ni 0.8 Co 0.2 OOH, Ni 0.8 Co 0.2 (OH) 2, etc. In the case of Ni 0.5 Mn 0.5 OOH or the like, in the case where the N element is a compound containing nickel, cobalt and manganese, Ni 0.4 Co 0.2 Mn 0.4 (OH) 2 , Ni 1/3 Co 1/3 Mn 1/3 OOH and the like are preferably exemplified.
本発明で使用されるリチウム原料化合物としては、炭酸リチウムあるいは水酸化リチウムが好ましく使用される。特に炭酸リチウムが安価で好ましい。また、必要に応じて使用されるフッ素原料化合物としては、金属フッ化物、ＬｉＦ、ＭｇＦ2などが選択される。 As the lithium raw material compound used in the present invention, lithium carbonate or lithium hydroxide is preferably used. In particular, lithium carbonate is preferable because it is inexpensive. Further, as the fluorine raw material compound used as necessary, metal fluoride, LiF, MgF 2 or the like is selected.
本発明において、上記の各原料化合物からリチウム含有複合酸化物を製造する場合、各種の具体的手段が採り得るが、その好ましい態様としては次の（Ａ）、（Ｂ）及び（Ｃ）の如き手段が挙げられる。
（Ａ）リチウム原料化合物、Ｎ元素原料化合物及び必要に応じてフッ素原料化合物と、前記有機金属化合物の有機溶媒溶液とを混合した後、得られる混合物から溶媒を除去し、酸素含有雰囲気において焼成する。
（Ｂ）Ｎ元素原料化合物及び必要に応じてフッ素原料化合物と、前記有機金属化合物の有機溶媒溶液とを混合し、得られる混合物から溶媒を除去した後、次いでリチウム原料化合物を混合し、得られる混合物を酸素含有雰囲気において焼成する。
（Ｃ）リチウム原料化合物、Ｎ元素原料化合物、及び必要に応じてフッ素原料化合物の混合物を酸素含有雰囲気で焼成して得られるリチウム複合酸化物と、前記有機金属化合物の有機溶媒溶液とを混合し、得られる混合物から溶媒を除去し、酸素含有雰囲気において焼成する。
In the present invention, when a lithium-containing composite oxide is produced from each of the above raw material compounds, various specific means can be taken, and preferred embodiments thereof include the following (A), (B) and (C). Means are mentioned.
(A) After mixing a lithium raw material compound, an N element raw material compound and, if necessary, a fluorine raw material compound and an organic solvent solution of the organometallic compound, the solvent is removed from the resulting mixture and baked in an oxygen-containing atmosphere. .
(B) N element raw material compound and, if necessary, a fluorine raw material compound and an organic solvent solution of the organometallic compound are mixed, and after removing the solvent from the resulting mixture, the lithium raw material compound is then mixed to obtain The mixture is fired in an oxygen-containing atmosphere.
(C) A lithium composite oxide obtained by firing a mixture of a lithium raw material compound, an N element raw material compound, and, if necessary, a fluorine raw material compound in an oxygen-containing atmosphere and an organic solvent solution of the organometallic compound are mixed. Then, the solvent is removed from the obtained mixture, and the mixture is fired in an oxygen-containing atmosphere.
上記（Ａ）、（Ｂ）及び（Ｃ）の如き手段により製造される場合、元素の原料化合物を粉末として使用する場合は、該粉末の平均粒径は、特に制限されるものではないが、良好な混合が達成されるために、好ましくは０．１〜２０μｍ、特に好ましくは０．５〜１５μｍが選択される。また、原料化合物の混合比率は、本発明で製造する正極活物質の一般式である上記ＬipＮxＭyＬｚＯｑＦaの範囲内で所望とする元素の比率になるように選択される。 When produced by means such as the above (A), (B) and (C), when the elemental raw material compound is used as a powder, the average particle diameter of the powder is not particularly limited, In order to achieve good mixing, preferably 0.1-20 μm, particularly preferably 0.5-15 μm is selected. The mixing ratio of the starting compound, chosen so that the ratio of the elements to be desired in the range of a general formula of the positive electrode active material prepared in the present invention the Li p N x M y L z O q F a Is done.
上記（Ａ）、（Ｂ）及び（Ｃ）の手段における有機金属化合物の有機溶媒溶液と原料化合物粉末との混合は、好ましくはアキシアルミキサー、パドルミキサーなどを使用し、スラリーを形成するように充分に均一に混合することが好ましい。スラリー中の固形分濃度としては、均一に混合される限り高い濃度の方が好ましいが、通常、固体／液体比（重量比）は５０／５０〜９０／１０、特に好ましくは６０／４０〜８０／２０が好適である。 The mixing of the organic solvent solution of the organometallic compound and the raw material compound powder in the means (A), (B) and (C) is preferably sufficient to form a slurry using an axial mixer, paddle mixer or the like. It is preferable to mix uniformly. The solid concentration in the slurry is preferably as high as possible as long as it is uniformly mixed. Usually, the solid / liquid ratio (weight ratio) is 50/50 to 90/10, particularly preferably 60/40 to 80. / 20 is preferred.
また、上記のようにスラリーを形成せずに、原料混合物粉末の混合物中に有機金属化合物の有機溶媒溶液をスプレー等によって噴霧し、均一に混合した湿潤粉末を用いることもできる。この場合の噴霧量は、固体／液体比（重量比）で９０／１０〜９５／５が好ましい。 Alternatively, a wet powder in which an organic solvent solution of an organometallic compound is sprayed into a mixture of raw material mixture powders by spraying or the like without forming a slurry as described above can also be used. The spray amount in this case is preferably 90/10 to 95/5 in solid / liquid ratio (weight ratio).
得られる各原料化合物を含む混合物からの有機溶媒の除去は、好ましくは５０〜２００℃、特に好ましくは８０〜１２０℃にて、通常１〜１０時間乾燥することにより行われる。混合物中の有機溶媒は、後の焼成工程で焼却されるために、この段階で必ずしも完全に除去する必要はないが、焼成工程で溶媒を飛ばすのに多量のエネルギーが必要になる上、爆発等の恐れもあるので、できる限り除去しておくのが好ましい。 Removal of the organic solvent from the resulting mixture containing each raw material compound is preferably carried out by drying at 50 to 200 ° C., particularly preferably at 80 to 120 ° C., usually for 1 to 10 hours. Since the organic solvent in the mixture is incinerated in a later baking step, it is not always necessary to completely remove it at this stage, but a large amount of energy is required to blow off the solvent in the baking step, and an explosion, etc. Therefore, it is preferable to remove as much as possible.
有機溶媒を除去した後の焼成は、上記（Ａ）及び（Ｂ）の手段においては、酸素含有雰囲気下において８００〜１０５０℃で行われる。かかる焼成温度が、８００℃より小さい場合にはリチウム複合酸化物化が不完全となり、逆に１０５０℃を超える場合には充放電サイクル耐久性や初期容量が低下してしまう。特に、焼成温度は９００〜１０００℃が好適である。また、上記（Ｃ）の手段では、既にリチウム複合酸化物粉末が形成されているので、酸素含有雰囲気下において３００〜１０５０℃で行われる。 Firing after removing the organic solvent is performed at 800 to 1050 ° C. in an oxygen-containing atmosphere in the above means (A) and (B). When the firing temperature is lower than 800 ° C., the lithium composite oxide is not completely formed. On the other hand, when it exceeds 1050 ° C., charge / discharge cycle durability and initial capacity are lowered. In particular, the firing temperature is preferably 900 to 1000 ° C. In the above means (C), since the lithium composite oxide powder has already been formed, it is carried out at 300 to 1050 ° C. in an oxygen-containing atmosphere.
このようにして製造される本発明のリチウム含有複合酸化物は、その平均粒径Ｄ５０が好ましくは５〜１５μｍ、特に好ましくは８〜１２μｍ、比表面積が好ましくは０．３〜０．７ｍ2／ｇ、特に好ましくは０．３〜０．５ｍ2／ｇ、ＣｕＫαを線源とするＸ線回折によって測定される２θ＝６６．５±１°の（１１０）面回折ピーク半値幅が好ましくは０．０８〜０．１４°特に好ましくは０．０８〜０．１２°、かつプレス密度が好ましくは３．１５〜３．６０ｇ／ｃｍ3、特に好ましくは３．２０〜３．５０ｇ／ｃｍ3であるのが好適である。また、本発明のリチウム含有複合酸化物は、含有される残存アルカリ量が０．０３質量％以下が好ましく、特には０．０１質量％以下であるのが好適である。 The lithium-containing composite oxide of the present invention thus produced has an average particle diameter D50 of preferably 5 to 15 μm, particularly preferably 8 to 12 μm, and a specific surface area of preferably 0.3 to 0.7 m 2 / g, particularly preferably 0.3 to 0.5 m 2 / g, (110) plane diffraction peak half-value width of 2θ = 66.5 ± 1 ° measured by X-ray diffraction using CuKα as a radiation source is preferably 0 0.08 to 0.14 °, particularly preferably 0.08 to 0.12 °, and the press density is preferably 3.15 to 3.60 g / cm 3 , particularly preferably 3.20 to 3.50 g / cm 3 . Preferably there is. In the lithium-containing composite oxide of the present invention, the residual alkali content is preferably 0.03% by mass or less, and particularly preferably 0.01% by mass or less.
かかるリチウム含有複合酸化物からリチウム二次電池用の正極を製造する場合には、かかる複合酸化物の粉末に、アセチレンブラック、黒鉛、ケッチエンブラックなどのカーボン系導電材と結合材を混合することにより形成される。上記結合材には、好ましくは、ポリフッ化ビニリデン、ポリテトラフルオロエチレン、ポリアミド、カルボキシメチルセルロース、アクリル樹脂等が用いられる。本発明のリチウム含有複合酸化物の粉末、導電材及び結合材を溶媒又は分散媒を使用し、スラリー又は混練物とされる。これをアルミニウム箔、ステンレス箔などの正極集電体に塗布などにより担持せしめてリチウム二次電池用の正極が製造される。 When producing a positive electrode for a lithium secondary battery from such a lithium-containing composite oxide, the composite oxide powder is mixed with a carbon-based conductive material such as acetylene black, graphite, and Ketchen black and a binder. It is formed by. For the binder, polyvinylidene fluoride, polytetrafluoroethylene, polyamide, carboxymethyl cellulose, acrylic resin, or the like is preferably used. The lithium-containing composite oxide powder, conductive material and binder of the present invention are made into a slurry or kneaded product using a solvent or a dispersion medium. This is supported on a positive electrode current collector such as an aluminum foil or a stainless steel foil by coating or the like to produce a positive electrode for a lithium secondary battery.
本発明のリチウム含有複合酸化物を正極活物質に用いるリチウム二次電池において、セパレータとしては、多孔質ポリエチレン、多孔質ポリプロピレンのフィルムなどが使用される。また、電池の電解質溶液の溶媒としては、種々の溶媒が使用できるが、なかでも炭酸エステルが好ましい。炭酸エステルは環状、鎖状いずれも使用できる。環状炭酸エステルとしては、プロピレンカーボネート、エチレンカーボネート（ＥＣ）などが例示される。鎖状炭酸エステルとしては、ジメチルカーボネート、ジエチルカーボネート（ＤＥＣ）、エチルメチルカーボネート（ＥＭＣ）、メチルプロピルカーボネート、メチルイソプロピルカーボネートなどが例示される。 In the lithium secondary battery using the lithium-containing composite oxide of the present invention as the positive electrode active material, a porous polyethylene film, a porous polypropylene film, or the like is used as the separator. Various solvents can be used as the solvent for the electrolyte solution of the battery, and among them, carbonate ester is preferable. The carbonate ester can be either cyclic or chain. Examples of cyclic carbonates include propylene carbonate and ethylene carbonate (EC). Examples of the chain carbonate include dimethyl carbonate, diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl propyl carbonate, methyl isopropyl carbonate, and the like.
本発明では、上記炭酸エステルを単独で又は２種以上を混合して使用できる。また、他の溶媒と混合して使用してもよい。また、負極活物質の材料によっては、鎖状炭酸エステルと環状炭酸エステルを併用すると、放電特性、サイクル耐久性、充放電効率が改良できる場合がある。 In this invention, the said carbonate ester can be used individually or in mixture of 2 or more types. Moreover, you may mix and use with another solvent. Moreover, depending on the material of the negative electrode active material, when a chain carbonate ester and a cyclic carbonate ester are used in combination, discharge characteristics, cycle durability, and charge / discharge efficiency may be improved.
また、本発明のリチウム含有複合酸化物を正極活物質に用いるリチウム二次電池においては、フッ化ビニリデン−ヘキサフルオロプロピレン共重合体（例えばアトケム社製：商品名カイナー）あるいはフッ化ビニリデン−パーフルオロプロピルビニルエーテル共重合体を含むゲルポリマー電解質としても良い。上記の電解質溶媒又はポリマー電解質に添加される溶質としては、ＣｌＯ4 −、ＣＦ3ＳＯ3 −、ＢＦ4 −、ＰＦ6 −、ＡｓＦ6 −、ＳｂＦ6 −、ＣＦ3ＣＯ2 −、（ＣＦ3ＳＯ2）2Ｎ−などをアニオンとするリチウム塩のいずれか１種以上が好ましく使用される。上記リチウム塩からなる電解質溶媒又はポリマー電解質に対して、０．２〜２．０ｍｏｌ／ｌ（リットル）の濃度で添加するのが好ましい。この範囲を逸脱すると、イオン伝導度が低下し、電解質の電気伝導度が低下する。なかでも、０．５〜１．５ｍｏｌ／ｌが特に好ましい。 In the lithium secondary battery using the lithium-containing composite oxide of the present invention as the positive electrode active material, a vinylidene fluoride-hexafluoropropylene copolymer (for example, product name: Kyner manufactured by Atchem Co.) or vinylidene fluoride-perfluoro is used. A gel polymer electrolyte containing a propyl vinyl ether copolymer may be used. Solutes added to the electrolyte solvent or polymer electrolyte include ClO 4 − , CF 3 SO 3 − , BF 4 − , PF 6 − , AsF 6 − , SbF 6 − , CF 3 CO 2 − , (CF 3 Any one or more of lithium salts having SO 2 ) 2 N − or the like as an anion is preferably used. It is preferable to add at a concentration of 0.2 to 2.0 mol / l (liter) with respect to the electrolyte solvent or polymer electrolyte made of the lithium salt. If it deviates from this range, the ionic conductivity is lowered and the electrical conductivity of the electrolyte is lowered. Of these, 0.5 to 1.5 mol / l is particularly preferable.
本発明のリチウム含有複合酸化物を正極活物質に用いるリチウム二次電池において、負極活物質には、リチウムイオンを吸蔵、放出可能な材料が用いられる。この負極活物質を形成する材料は特に限定されないが、例えばリチウム金属、リチウム合金、炭素材料、周期表１４、又は１５族の金属を主体とした酸化物、炭素化合物、炭化ケイ素化合物、酸化ケイ素化合物、硫化チタン、炭化ホウ素化合物などが挙げられる。炭素材料としては、種々の熱分解条件で有機物を熱分解したものや人造黒鉛、天然黒鉛、土壌黒鉛、膨張黒鉛、鱗片状黒鉛などを使用できる。また、酸化物としては、酸化スズを主体とする化合物が使用できる。負極集電体としては、銅箔、ニッケル箔などが用いられる。かかる負極は、上記活物質を有機溶媒と混練してスラリーとし、該スラリーを金属箔集電体に塗布、乾燥、プレスして得ることにより好ましくは製造される。 In the lithium secondary battery using the lithium-containing composite oxide of the present invention as the positive electrode active material, a material capable of inserting and extracting lithium ions is used as the negative electrode active material. The material for forming the negative electrode active material is not particularly limited. For example, an oxide, a carbon compound, a silicon carbide compound, or a silicon oxide compound mainly composed of lithium metal, lithium alloy, carbon material, periodic table 14 or group 15 metal. , Titanium sulfide, boron carbide compounds and the like. As the carbon material, those obtained by pyrolyzing an organic substance under various pyrolysis conditions, artificial graphite, natural graphite, soil graphite, expanded graphite, flake graphite, and the like can be used. As the oxide, a compound mainly composed of tin oxide can be used. As the negative electrode current collector, a copper foil, a nickel foil, or the like is used. Such a negative electrode is preferably produced by kneading the active material with an organic solvent to form a slurry, and applying the slurry to a metal foil current collector, drying, and pressing.
本発明のリチウム含有複合酸化物を正極活物質に用いるリチウム二次電池の形状には特に制約はない。シート状、フィルム状、折り畳み状、巻回型有底円筒形、ボタン形などが用途に応じて選択される。 There is no restriction | limiting in particular in the shape of the lithium secondary battery which uses the lithium containing complex oxide of this invention for a positive electrode active material. A sheet shape, a film shape, a folded shape, a wound-type bottomed cylindrical shape, a button shape, or the like is selected depending on the application.
以下に実施例により本発明を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ないことはもちろんである。
［例１］
硫酸コバルト水溶液と水酸化アンモニウムの混合液と苛性ソーダ水溶液を連続的に混合して、連続的に水酸化コバルトスラリーを既知の方法により合成し、凝集、ろ過及び乾燥工程を経て水酸化コバルト粉体を得た。得られた水酸化コバルトは、ＣｕＫα線を使用した粉末Ｘ線回折において、２θ＝１９±１°の（００１）面の回折ピーク半値幅は０．２７°であり、２θ＝３８°±１の（１０１）面の回折ピーク半値幅は０．２３°であり、走査型電子顕微鏡観察の結果、微粒子が凝集して、略球状の二次粒子から形成されていることが判った。走査型電子顕微鏡観察の画像解析から求めた体積基準の粒度分布解析の結果、平均粒径Ｄ５０が１５．９μｍ、Ｄ１０が６．４μｍ、Ｄ９０が２１．７μｍであった。水酸化コバルトのコバルト含量は６２．０％であった。
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
[Example 1]
Cobalt sulfate aqueous solution and ammonium hydroxide mixed solution and caustic soda aqueous solution are continuously mixed to continuously synthesize a cobalt hydroxide slurry by a known method. Obtained. The obtained cobalt hydroxide has a diffraction peak half-width of (001) plane of 2θ = 19 ± 1 ° in powder X-ray diffraction using CuKα ray is 0.27 °, and 2θ = 38 ° ± 1. The diffraction peak half-value width of the (101) plane was 0.23 °, and as a result of observation with a scanning electron microscope, it was found that the fine particles were aggregated and formed from substantially spherical secondary particles. As a result of volume-based particle size distribution analysis obtained from image analysis under scanning electron microscope observation, the average particle size D50 was 15.9 μm, D10 was 6.4 μm, and D90 was 21.7 μm. The cobalt content of cobalt hydroxide was 62.0%.
上記水酸化コバルト１９１．８２ｇと、比表面積が１．２ｍ2／ｇの炭酸リチウム粉末７６．４３ｇとを混合した。 191.82 g of the above cobalt hydroxide and 76.43 g of lithium carbonate powder having a specific surface area of 1.2 m 2 / g were mixed.
一方、有機金属化合物である、０．６２ｍｏｌ／ｋｇの（２−エチルヘキサノエート）−Ｍｇ−Ｏ−Ａｌ（２−エチルヘキサノエート）（ｓｅｃ−ブトキシド）のキシレン溶液（Ａｌ１．６％、Ｍｇ１．５％）１３．６４ｇを、上記水酸化コバルトと炭酸リチウムとの混合物に対して、ＬｉＡｌ０．０１Ｃｏ０．９８Ｍｇ０．０１Ｏ2となるように加えてスラリー状に混合した。 On the other hand, a xylene solution of 0.62 mol / kg (2-ethylhexanoate) -Mg-O-Al (2-ethylhexanoate) (sec-butoxide), which is an organometallic compound (1.6% Al, 13.64 g of Mg1.5%) was added to the above mixture of cobalt hydroxide and lithium carbonate so as to be LiAl 0.01 Co 0.98 Mg 0.01 O 2 and mixed in a slurry state.
このスラリーを１２０℃で２時間、乾燥機にて脱溶媒した後、酸素含有雰囲気中、９５０℃で１２時間焼成した。焼成物を解砕し得られた１次粒子が凝集してなるリチウム含有複合酸化物粉末の粒度分布をレーザー散乱式粒度分布測定装置を用いて水溶媒中にて測定した結果、平均粒径Ｄ５０が１５．８μｍ、Ｄ１０が６．２μｍ、Ｄ９０が２１．５μｍであり、ＢＥＴ法により求めた比表面積が０．３３ｍ2／ｇの略球状のリチウム含有複合酸化物粉末を得た。 The slurry was desolvated with a dryer at 120 ° C. for 2 hours, and then calcined at 950 ° C. for 12 hours in an oxygen-containing atmosphere. As a result of measuring the particle size distribution of the lithium-containing composite oxide powder obtained by agglomerating primary particles obtained by crushing the fired product in a water solvent using a laser scattering type particle size distribution measuring device, the average particle size D50 Was 15.8 μm, D10 was 6.2 μm, D90 was 21.5 μm, and a substantially spherical lithium-containing composite oxide powder having a specific surface area of 0.33 m 2 / g determined by the BET method was obtained.
このリチウム含有複合酸化物粉末について、Ｘ線回折装置（理学電機社製ＲＩＮＴ ２１００型）を用いてＸ線回折スペクトルを得た。ＣｕＫα線を使用した粉末Ｘ線回折において、２θ＝６６．５±１°の（１１０）面の回折ピーク半値幅は０．１１４°であった。この粉末のプレス密度は３．２２ｇ／ｃｍ3であった。このリチウムコバルト複合酸化物粉末１０ｇを純水１００ｇ中に分散し、濾過後０．１ＮＨＣｌで電位差滴定して残存アルカリ量を求めたところ、０．０２質量％であった。 With respect to this lithium-containing composite oxide powder, an X-ray diffraction spectrum was obtained using an X-ray diffractometer (RINT 2100 type, manufactured by Rigaku Corporation). In powder X-ray diffraction using CuKα ray, the half value width of the diffraction peak of (110) plane at 2θ = 66.5 ± 1 ° was 0.114 °. The press density of this powder was 3.22 g / cm 3 . 10 g of this lithium cobalt composite oxide powder was dispersed in 100 g of pure water, filtered, and potentiometrically titrated with 0.1 N HCl to determine the residual alkali amount, which was 0.02% by mass.
上記のリチウム含有複合酸化物粉末と、アセチレンブラックと、ポリフッ化ビニリデン粉末とを９０／５／５の質量比で混合し、Ｎ−メチルピロリドンを添加してスラリーを作製し、厚さ２０μｍのアルミニウム箔にドクターブレードを用いて片面塗工した。乾燥し、ロールプレス圧延を５回行うことによりリチウム電池用の正極体シートを作製した。 The lithium-containing composite oxide powder, acetylene black, and polyvinylidene fluoride powder are mixed at a mass ratio of 90/5/5, N-methylpyrrolidone is added to prepare a slurry, and aluminum having a thickness of 20 μm is prepared. The foil was coated on one side using a doctor blade. The positive electrode sheet for lithium batteries was produced by drying and performing roll press rolling 5 times.
そして、上記正極体シートを打ち抜いたものを正極に用い、厚さ５００μｍの金属リチウム箔を負極に用い、負極集電体にニッケル箔２０μｍを使用し、セパレータには厚さ２５μｍの多孔質ポリプロピレンを用い、さらに電解液には、濃度１ＭのＬｉＰＦ6／ＥＣ＋ＤＥＣ（１：１）溶液（ＬｉＰＦ6を溶質とするＥＣとＤＥＣとの質量比（１：１）の混合溶液を意味する。後記する溶媒もこれに準じる。）を用いてステンレス製簡易密閉セル型リチウム二次電池をアルゴングローブボックス内で２個組み立てた。 The positive electrode sheet is punched out as a positive electrode, a metal lithium foil having a thickness of 500 μm is used as a negative electrode, a nickel foil of 20 μm is used as a negative electrode current collector, and a porous polypropylene having a thickness of 25 μm is used as a separator. Further, the electrolytic solution used is a LiPF 6 / EC + DEC (1: 1) solution having a concentration of 1 M (meaning a mixed solution of EC and DEC having a mass ratio (1: 1) of LiPF 6 as a solute. Solvents described later) In accordance with this, two stainless steel simple sealed cell type lithium secondary batteries were assembled in an argon glove box.
上記１個の電池については、２５℃にて正極活物質１ｇにつき７５ｍＡの負荷電流で４．３Ｖまで充電し、正極活物質１ｇにつき７５ｍＡの負荷電流にて２．５Ｖまで放電して初期放電容量を求めた。さらに電極層の密度を求めた。また、この電池について、引き続き充放電サイクル試験を３０回行なった。その結果、２５℃、２．５〜４．３Ｖにおける正極電極層の初期重量容量密度は、１６２ｍＡｈ／ｇであり、３０回充放電サイクル後の容量維持率は９９．１％であった。 For the one battery, the initial discharge capacity was charged at 25 ° C. with a load current of 75 mA per gram of the positive electrode active material to 4.3 V and discharged with a load current of 75 mA per gram of the positive electrode active material to 2.5 V. Asked. Furthermore, the density of the electrode layer was determined. Moreover, about this battery, the charging / discharging cycle test was done 30 times continuously. As a result, the initial weight capacity density of the positive electrode layer at 25 ° C. and 2.5 to 4.3 V was 162 mAh / g, and the capacity retention rate after 30 charge / discharge cycles was 99.1%.
また、他方の電池については、それぞれ４．３Ｖで１０時間充電し、アルゴングローブボックス内で解体し、充電後の正極体シートを取り出し、その正極体シートを洗滌後、径３ｍｍに打ち抜き、ＥＣとともにアルミカプセルに密閉し、走査型差動熱量計にて５℃／分の速度で昇温して発熱開始温度を測定した。その結果、４．３Ｖ充電品の発熱開始温度は１７２℃であった。 The other battery was charged at 4.3 V for 10 hours, disassembled in an argon glove box, taken out from the charged positive electrode sheet, washed out, then punched into a diameter of 3 mm, and with EC The container was sealed in an aluminum capsule and heated at a rate of 5 ° C./min with a scanning differential calorimeter to measure the heat generation start temperature. As a result, the heat generation start temperature of the 4.3V charged product was 172 ° C.
［例２］
例１において用いた上記水酸化コバルト１９１．４２ｇと、有機金属化合物である、（ネオデカノエート）−Ｚｒ（＝Ｏ）−Ｏ−Ｐ（＝Ｏ）（ブトキサイド）２をキシレンに溶解させて１ｍｏｌ／ｋｇにした溶液（Ｚｒ９．１％、Ｐ３．１％を含有する）９．９５ｇとを混合した。得られるスラリーを１２０℃で２時間、乾燥機にて脱溶媒した後、炭酸リチウム７５．７３ｇを加えて、混合した他は例１と同様にして正極活物質を合成した。
[Example 2]
191.42 g of the cobalt hydroxide used in Example 1 and (neodecanoate) -Zr (= O) -OP (= O) (butoxide) 2 as an organometallic compound were dissolved in xylene to give 1 mol / kg. And 9.95 g of the solution (containing Zr 9.1%, P 3.1%). The resulting slurry was desolvated with a drier at 120 ° C. for 2 hours, and then a positive electrode active material was synthesized in the same manner as in Example 1 except that 75.73 g of lithium carbonate was added and mixed.
焼成後ＬｉＣｏ０．９８７Ｚｒ０．０１Ｐ０．００３Ｏ２を得た。焼成物を解砕し得られた１次粒子が凝集してなるリチウム含有複合酸化物粉末の粒度分布をレーザー散乱式粒度分布測定装置を用いて測定した結果、平均粒径Ｄ５０が１５．７μｍ、Ｄ１０が６．５μｍ、Ｄ９０が２１．５μｍであり、ＢＥＴ法により求めた比表面積が０．３３ｍ2／ｇの略球状の粉末を得た。この粉末について、Ｘ線回折装置（理学電機社製ＲＩＮＴ ２１００型）を用いてＸ線回折スペクトルを得た。ＣｕＫα線を使用した粉末Ｘ線回折において、２θ＝６６．５±１°付近の（１１０）面の回折ピーク半値幅は０．１１８°であった。上記粉末のプレス密度は３．２３ｇ／ｃｍ3であった。また、上記粉末１０ｇを純水１００ｇ中に分散し、濾過後０．１ＮＨＣｌで電位差滴定して残存アルカリ量を求めたところ、０．０２質量％であった。 After firing, LiCo 0.987 Zr 0.01 P 0.003 O 2 was obtained. As a result of measuring the particle size distribution of the lithium-containing composite oxide powder obtained by agglomerating primary particles obtained by crushing the fired product using a laser scattering particle size distribution measuring device, the average particle size D50 is 15.7 μm, A substantially spherical powder having a D10 of 6.5 μm, a D90 of 21.5 μm and a specific surface area of 0.33 m 2 / g determined by the BET method was obtained. With respect to this powder, an X-ray diffraction spectrum was obtained using an X-ray diffractometer (RINT 2100 type, manufactured by Rigaku Corporation). In powder X-ray diffraction using CuKα ray, the half value width of the diffraction peak of (110) plane in the vicinity of 2θ = 66.5 ± 1 ° was 0.118 °. The press density of the powder was 3.23 g / cm 3 . Further, 10 g of the above powder was dispersed in 100 g of pure water, filtered and subjected to potentiometric titration with 0.1N HCl to determine the residual alkali amount, which was 0.02% by mass.
上記のリチウム含有複合酸化物粉末を使用し、例１と同様にして、正極体を製造し、電池を組み立てて、その特性を測定した。正極電極層の初期重量容量密度は、１６２ｍＡｈ／ｇであり、３０回充放電サイクル後の容量維持率は９９．２％であった。４．３Ｖ充電品の発熱開始温度は１７３℃であった。 Using the above lithium-containing composite oxide powder, a positive electrode body was produced in the same manner as in Example 1, a battery was assembled, and its characteristics were measured. The initial weight capacity density of the positive electrode layer was 162 mAh / g, and the capacity retention rate after 30 charge / discharge cycles was 99.2%. The heat generation start temperature of the 4.3V charged product was 173 ° C.
［例３］比較例
例１に用いた添加液の代わりに、水酸化アルミニウム１．６１ｇと水酸化マグネシウム１．２０ｇとを用い、上記水酸化コバルト１９１．８２ｇと、炭酸リチウム７６．４３ｇとを混合した。この混合物を、酸素含有雰囲気中、９５０℃で１２時間焼成した。焼成後ＬｉＡｌ０．０１Ｃｏ０．９８Ｍｇ０．０１Ｏ2であるリチウム含有複合酸化物を合成した。平均粒径Ｄ５０が１６．０μｍ、Ｄ１０が６．４μｍ、Ｄ９０が２２．１μｍであり、ＢＥＴ法により求めた比表面積が０．３３ｍ2／ｇの塊状のリチウム含有複合酸化物粉末を得た。
[Example 3] Comparative Example Instead of the additive solution used in Example 1, 1.61 g of aluminum hydroxide and 1.20 g of magnesium hydroxide were used, and 191.82 g of the above cobalt hydroxide and 76.43 g of lithium carbonate were used. Mixed. This mixture was baked at 950 ° C. for 12 hours in an oxygen-containing atmosphere. After firing, a lithium-containing composite oxide that was LiAl 0.01 Co 0.98 Mg 0.01 O 2 was synthesized. An agglomerated lithium-containing composite oxide powder having an average particle diameter D50 of 16.0 μm, D10 of 6.4 μm, D90 of 22.1 μm, and a specific surface area determined by the BET method of 0.33 m 2 / g was obtained.
この粉末について、Ｘ線回折装置（理学電機社製ＲＩＮＴ ２１００型）を用いてＸ線回折スペクトルを得た。ＣｕＫα線を使用した粉末Ｘ線回折において、２θ＝６６．５±１°付近の（１１０）面の回折ピーク半値幅は０．１１９°であった。得られた粉末のプレス密度は３．０３ｇ／ｃｍ3であった。 With respect to this powder, an X-ray diffraction spectrum was obtained using an X-ray diffractometer (RINT 2100 type, manufactured by Rigaku Corporation). In powder X-ray diffraction using CuKα ray, the half value width of the diffraction peak of (110) plane in the vicinity of 2θ = 66.5 ± 1 ° was 0.119 °. The press density of the obtained powder was 3.03 g / cm 3 .
例１と同様にして、正極体を製造し、電池を組み立てて、その特性を測定した。正極電極層の初期重量容量密度は、１５９ｍＡｈ／ｇであり、３０回充放電サイクル後の容量維持率は９７．７％であった。４.３Ｖ充電品の発熱開始温度は１６８℃であった。 In the same manner as in Example 1, a positive electrode body was manufactured, a battery was assembled, and its characteristics were measured. The initial weight capacity density of the positive electrode layer was 159 mAh / g, and the capacity retention after 30 charge / discharge cycles was 97.7%. The heat generation start temperature of the 4.3V charged product was 168 ° C.
［例４］比較例
例２に用いた添加液の代わりに、酸化ジルコニウム２．５１ｇとリン酸三アンモニウム三水和物１．２４ｇとを用い、上記水酸化コバルト１９１．４２ｇと炭酸リチウム７５．７３ｇとを混合した。この混合物を、酸素含有雰囲気中、９５０℃で１２時間焼成した。焼成後ＬｉＺｒ０．０１Ｃｏ０．９８７Ｐ０．００３Ｏ2であるリチウム含有複合酸化物を合成した。平均粒径Ｄ５０が１５．５μｍ、Ｄ１０が６．２μｍ、Ｄ９０が２１．４μｍであり、ＢＥＴ法により求めた比表面積が０．３５ｍ2／ｇの塊状のリチウム含有複合酸化物粉末を得た。この粉末について、Ｘ線回折装置（理学電機社製ＲＩＮＴ ２１００型）を用いてＸ線回折スペクトルを得た。ＣｕＫα線を使用した粉末Ｘ線回折において、２θ＝６６．５±１°付近の（１１０）面の回折ピーク半値幅は０．１２０°であった。得られた粉末のプレス密度は３．０１ｇ／ｃｍ3であった。
[Example 4] Comparative Example Instead of the additive solution used in Example 2, 2.51 g of zirconium oxide and 1.24 g of triammonium phosphate trihydrate were used, and 191.42 g of the above cobalt hydroxide and 75. 73 g was mixed. This mixture was baked at 950 ° C. for 12 hours in an oxygen-containing atmosphere. After firing, a lithium-containing composite oxide that was LiZr 0.01 Co 0.987 P 0.003 O 2 was synthesized. An agglomerated lithium-containing composite oxide powder having an average particle diameter D50 of 15.5 μm, D10 of 6.2 μm, D90 of 21.4 μm and a specific surface area determined by the BET method of 0.35 m 2 / g was obtained. With respect to this powder, an X-ray diffraction spectrum was obtained using an X-ray diffractometer (RINT 2100 type, manufactured by Rigaku Corporation). In powder X-ray diffraction using CuKα ray, the half value width of the diffraction peak of (110) plane in the vicinity of 2θ = 66.5 ± 1 ° was 0.120 °. The press density of the obtained powder was 3.01 g / cm 3 .
例１と同様にして、正極体を製造し、電池を組み立てて、その特性を測定した。正極電極層の初期重量容量密度は、１５８ｍＡｈ／ｇであり、３０回充放電サイクル後の容量維持率は９７．７％であった。４.３Ｖ充電品の発熱開始温度は１６６℃であった。 In the same manner as in Example 1, a positive electrode body was manufactured, a battery was assembled, and its characteristics were measured. The initial weight capacity density of the positive electrode layer was 158 mAh / g, and the capacity retention rate after 30 charge / discharge cycles was 97.7%. The heat generation start temperature of the 4.3V charged product was 166 ° C.
［例５］
上記水酸化コバルト１９４．２４ｇと炭酸リチウム７５．８５ｇとを混合し、酸素含有雰囲気中、９５０℃で１２時間焼成して、ＬｉＣｏＯ２となるように正極活物質を合成した。有機金属化合物である、０．６２ｍｏｌ／ｋｇの（２−エチルヘキサノエート）−Ｍｇ−Ｏ−Ａｌ（２−エチルヘキサノエート）（ｓｅｃ−ブトキサイド）のキシレン溶液（Ａｌ％、Ｍｇ％）６．８２ｇと、（ネオデカノエート）−Ｚｒ（＝Ｏ）−Ｏ−Ｏ（＝Ｏ）（ブトキサイド）２をキシレンに溶解させて１ｍｏｌ／ｋｇにした溶液４．９８ｇとを混合したものを用い、上記ＬｉＣｏＯ２粉末１００ｇに対して、ＬｉＡｌ０．０１Ｃｏ０．９７６Ｍｇ０．０１Ｚｒ０．００３Ｐ０．００１Ｏ2となるように混合し、スラリー状にした。このスラリーを１２０℃で２時間、乾燥機にて脱溶媒した後、酸素含有雰囲気中、９５０℃で１２時間焼成した。
[Example 5]
The above-mentioned cobalt hydroxide 194.24 g and lithium carbonate 75.85 g were mixed and fired at 950 ° C. for 12 hours in an oxygen-containing atmosphere to synthesize a positive electrode active material so as to be LiCoO 2 . 0.62 mol / kg (2-ethylhexanoate) -Mg-O-Al (2-ethylhexanoate) (sec-butoxide) xylene solution (Al%, Mg%) 6 which is an organometallic compound .82 g and (Neodecanoate) -Zr (═O) —O—O (═O) (butoxide) 2 were dissolved in xylene and mixed with 4.98 g of 1 mol / kg solution, and the above LiCoO was used. Two powders (100 g) were mixed so as to be LiAl 0.01 Co 0.976 Mg 0.01 Zr 0.003 P 0.001 O 2 to form a slurry. The slurry was desolvated with a dryer at 120 ° C. for 2 hours, and then calcined at 950 ° C. for 12 hours in an oxygen-containing atmosphere.
この粉末のプレス密度は ３．２１ｇ／ｃｍ3であった。また、この粉末１０ｇを純水１００ｇ中に分散し、濾過後０．１ＮＨＣｌで電位差滴定して残存アルカリ量を求めたところ、０．０２質量％であった。 The press density of this powder was 3.21 g / cm 3 . Further, 10 g of this powder was dispersed in 100 g of pure water, filtered and subjected to potentiometric titration with 0.1N HCl to obtain the residual alkali amount, which was 0.02% by mass.
例１と同様にして、正極体を製造し、電池を組み立てて、その特性を測定した。正極電極層の初期重量容量密度は１６３ｍＡｈ／ｇ、３０回サイクル後の容量維持率は９９．３％、発熱開始温度は１７５℃であった。 In the same manner as in Example 1, a positive electrode body was manufactured, a battery was assembled, and its characteristics were measured. The initial weight capacity density of the positive electrode layer was 163 mAh / g, the capacity retention rate after 30 cycles was 99.3%, and the heat generation starting temperature was 175 ° C.
［例６］比較例
上記水酸化コバルト１９０．８５ｇ、炭酸リチウム７６．３６ｇ、水酸化アルミニウム１．６０ｇ、水酸化マグネシウム１．２０ｇ、酸化ジルコニウム０．７６ｇ、リン酸三アンモニウム三水和物０．４２ｇとを混合した。この混合物を、酸素含有雰囲気中、９５０℃で１２時間焼成した。焼成後ＬｉＡｌ０．０１Ｃｏ０．９７６Ｍｇ０．０１Ｚｒ０．００３Ｐ０．００１Ｏ2となる正極活物質を得た。
[Example 6] Comparative Example 190.85 g of the above cobalt hydroxide, 76.36 g of lithium carbonate, 1.60 g of aluminum hydroxide, 1.20 g of magnesium hydroxide, 0.76 g of zirconium oxide, triammonium phosphate trihydrate 42 g was mixed. This mixture was baked at 950 ° C. for 12 hours in an oxygen-containing atmosphere. To obtain a positive electrode active material comprising after firing LiAl 0.01 Co 0.976 Mg 0.01 Zr 0.003 P 0.001 O 2.
この粉末のプレス密度は３．０１ｇ／ｃｍ3であった。また、例１と同様にして、正極体を製造し、電池を組み立てて、その特性を測定した。正極電極層の初期重量容量密度は１５９ｍＡｈ／ｇ、３０回サイクル後の容量維持率は９７．９％、発熱開始温度１６９℃であった。 The press density of this powder was 3.01 g / cm 3 . Moreover, it carried out similarly to Example 1, the positive electrode body was manufactured, the battery was assembled, and the characteristic was measured. The initial weight capacity density of the positive electrode layer was 159 mAh / g, the capacity retention after 30 cycles was 97.9%, and the heat generation start temperature was 169 ° C.
［例７］
例１にて用いた上記水酸化コバルト１９１．６０ｇと、有機金属化合物である、（ネオデカノエート）−Ｚｒ（＝Ｏ）−Ｏ−Ｐ（＝Ｏ）（ブトキサイド）２をキシレンに溶解させて１ｍｏｌ／ｋｇにした溶液（Ｚｒ９．１％、Ｐ３．１％を含有する）９．９５ｇとを混合し、このスラリーを１２０℃で２時間、乾燥機にて脱溶媒した後、炭酸リチウム７５．９６ｇと、フッ化リチウム２．６７ｇを加えて、混合した。例１と同様にして正極活物質を合成した。焼成後の組成はＬｉＡｌ０．０１Ｃｏ０．９８Ｍｇ０．０１Ｏ１．９９Ｆ０．０１であった。この粉末のプレス密度は３．２０ｇ／ｃｍ3であった。
[Example 7]
191.60 g of the cobalt hydroxide used in Example 1 and (neodecanoate) -Zr (= O) -OP (= O) (butoxide) 2 as an organometallic compound were dissolved in xylene to give 1 mol / The resulting solution was mixed with 9.95 g of a kg solution (containing 9.1% Zr and 3.1% Pr), the slurry was desolvated in a dryer at 120 ° C. for 2 hours, and then 75.96 g of lithium carbonate was added. Then, 2.67 g of lithium fluoride was added and mixed. A positive electrode active material was synthesized in the same manner as in Example 1. The composition after firing was LiAl 0.01 Co 0.98 Mg 0.01 O 1.99 F 0.01 . The press density of this powder was 3.20 g / cm 3 .
また、例１と同様にして、正極体を製造し、電池を組み立てて、その特性を測定した。正極電極層の初期重量容量密度は１６０ｍＡｈ／ｇ、３０回サイクル後の容量維持率は９９．３％、発熱開始温度１７６℃であった。 Moreover, it carried out similarly to Example 1, the positive electrode body was manufactured, the battery was assembled, and the characteristic was measured. The initial weight capacity density of the positive electrode layer was 160 mAh / g, the capacity retention rate after 30 cycles was 99.3%, and the heat generation starting temperature was 176 ° C.
［例８］比較例
水酸化マグネシウム１．２０ｇ、水酸化アルミニウム１．６０ｇ、フッ化リチウム２．６７ｇを用い、上記水酸化コバルト１９１．６０ｇ、炭酸リチウム７５．９６ｇと混合した他は例２と同様に焼成して正極活物質を得た。焼成後の組成はＬｉＡｌ０．０１Ｃｏ０．９８Ｍｇ０．０１Ｏ１．９９Ｆ０．０１であった。この粉末のプレス密度は２．９８ｇ／ｃｍ3であった。
[Example 8] Comparative Example Example 1 except that 1.20 g of magnesium hydroxide, 1.60 g of aluminum hydroxide and 2.67 g of lithium fluoride were mixed with 191.60 g of cobalt hydroxide and 75.96 g of lithium carbonate. Similarly, firing was performed to obtain a positive electrode active material. The composition after firing was LiAl 0.01 Co 0.98 Mg 0.01 O 1.99 F 0.01 . The press density of this powder was 2.98 g / cm 3 .
また、例１と同様にして、正極体を製造し、電池を組み立てて、その特性を測定した。正極電極層の初期重量容量密度は１５８ｍＡｈ／ｇ、３０回サイクル後の容量維持率は９８．０％、発熱開始温度１７０℃であった。 Moreover, it carried out similarly to Example 1, the positive electrode body was manufactured, the battery was assembled, and the characteristic was measured. The initial weight capacity density of the positive electrode layer was 158 mAh / g, the capacity retention after 30 cycles was 98.0%, and the heat generation starting temperature was 170 ° C.
本発明によれば、体積容量密度が大きく、安全性が高く、及び充放電サイクル耐久性に優れたリチウム二次電池正極用のリチウム含有複合酸化物の製造方法、製造されたリチウムコバルト複合酸化物などのリチウム含有複合酸化物を含む、リチウム二次電池用正極、及びリチウム二次電池が提供される。 According to the present invention, a method for producing a lithium-containing composite oxide for a lithium secondary battery positive electrode having a large volumetric capacity density, high safety, and excellent charge / discharge cycle durability, and produced lithium cobalt composite oxide A positive electrode for a lithium secondary battery including a lithium-containing composite oxide, and a lithium secondary battery are provided.
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| KR101104663B1 (en) | 2007-03-30 | 2012-01-13 | 니폰 가가쿠 고교 가부시키가이샤 | Lithium transition metal complex oxide for lithium ion secondary battery positive electrode active material, producing method of lithium transition metal complex oxide, positive electrode active material for lithium ion secondary battery, and lithium ion secondary battery |
| JP2013077563A (en) * | 2011-09-16 | 2013-04-25 | Toyota Central R&D Labs Inc | Electrode material for lithium secondary battery, method for producing the same, and lithium secondary battery including the same |
| KR101520903B1 (en) * | 2010-03-29 | 2015-05-18 | 주식회사 포스코이에스엠 | Process for the production of lithium-manganese double oxide for lithium ion batteries and lithium-manganese double oxide for lithium ion batteries made by the same, and lithium ion batteries cotaining the same |
| WO2021111249A1 (en) * | 2019-12-04 | 2021-06-10 | 株式会社半導体エネルギー研究所 | Positive electrode active material, secondary battery, and vehicle |
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| KR101104663B1 (en) | 2007-03-30 | 2012-01-13 | 니폰 가가쿠 고교 가부시키가이샤 | Lithium transition metal complex oxide for lithium ion secondary battery positive electrode active material, producing method of lithium transition metal complex oxide, positive electrode active material for lithium ion secondary battery, and lithium ion secondary battery |
| KR101520903B1 (en) * | 2010-03-29 | 2015-05-18 | 주식회사 포스코이에스엠 | Process for the production of lithium-manganese double oxide for lithium ion batteries and lithium-manganese double oxide for lithium ion batteries made by the same, and lithium ion batteries cotaining the same |
| JP2013077563A (en) * | 2011-09-16 | 2013-04-25 | Toyota Central R&D Labs Inc | Electrode material for lithium secondary battery, method for producing the same, and lithium secondary battery including the same |
| US9130214B2 (en) | 2011-09-16 | 2015-09-08 | Kabushiki Kaisha Toyota Chuo Kenkyusho | Electrode material for lithium secondary battery, method for producing the same, and lithium secondary battery including the same |
| WO2021111249A1 (en) * | 2019-12-04 | 2021-06-10 | 株式会社半導体エネルギー研究所 | Positive electrode active material, secondary battery, and vehicle |
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