JP4954481B2 - Lithium secondary battery - Google Patents

Lithium secondary battery Download PDF

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JP4954481B2
JP4954481B2 JP2005049090A JP2005049090A JP4954481B2 JP 4954481 B2 JP4954481 B2 JP 4954481B2 JP 2005049090 A JP2005049090 A JP 2005049090A JP 2005049090 A JP2005049090 A JP 2005049090A JP 4954481 B2 JP4954481 B2 JP 4954481B2
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道夫 高橋
俊広 吉田
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NGK Insulators 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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Description

本発明は、リチウム二次電池に関し、さらに詳しくは、高温特性、特に高温保存特性に優れたリチウム二次電池に関する。   The present invention relates to a lithium secondary battery, and more particularly to a lithium secondary battery excellent in high temperature characteristics, particularly high temperature storage characteristics.

近年、携帯電話やＶＴＲ、ノート型パソコン等の携帯型電子機器の小型軽量化が加速度的に進行しており、その電源用電池として、リチウム遷移元素複合酸化物を含有した正極活物質、炭素質材料から構成された負極活物質、及びＬｉイオン電解質を有機溶媒に溶解した有機電解液を備えた二次電池が用いられるようになっている。   In recent years, portable electronic devices such as mobile phones, VTRs, notebook computers, etc. have been reduced in size and weight at an accelerated pace. As power batteries, positive electrode active materials containing lithium transition element composite oxides, carbonaceous materials A secondary battery including a negative electrode active material composed of a material and an organic electrolyte obtained by dissolving a Li ion electrolyte in an organic solvent is used.

このような電池は、一般的にリチウム二次電池又はリチウムイオン電池と称せられており、エネルギー密度が大きく、また、単電池電圧も約４Ｖ程度と高い特徴を有することから、上述の携帯型電子機器のみならず、最近の環境問題を背景に、低公害車として積極的な一般への普及が図られている電気自動車（ＥＶ）又はハイブリット電気自動車（ＨＥＶ）のモータ駆動電源としても注目を集めている。   Such a battery is generally called a lithium secondary battery or a lithium ion battery, and has a high energy density and a high single cell voltage of about 4V. It attracts attention not only as a device but also as a motor drive power source for electric vehicles (EV) or hybrid electric vehicles (HEV) that are actively popularized as low-pollution vehicles against the background of recent environmental problems. ing.

このようなリチウム二次電池において、その電池特性は、用いる正極活物質の材料特性に依存するところが大きい。ここで、正極活物質に含有されるリチウム遷移元素複合酸化物としては、具体的には、コバルト酸リチウム（ＬｉＣｏＯ2）、ニッケル酸リチウム（ＬｉＮｉＯ2）、マンガン酸リチウム（ＬｉＭｎ2Ｏ4）等が挙げられる。このような正極活物質の中で、安価で安全性に優れたスピネル構造を有するマンガン酸リチウムが主に使用されつつあるが、高温特性の改善が課題となっている。これまで、Ｍｎの一部を他の元素で置換する方法、マンガン酸リチウムの表面をコーティングする方法等が検討されているが、高温特性の向上という効果の面で必ずしも十分に満足し得るものではなかった。一方、マンガン酸リチウムと層状化合物とを混合するハイブリット型の正極活物質を用いたリチウム二次電池が開示されているが、同様に効果の面で必ずしも十分に満足し得るものではなかった（特許文献１参照）。
特開２００３−１６８４３０号公報 In such a lithium secondary battery, the battery characteristics largely depend on the material characteristics of the positive electrode active material used. Here, as the lithium transition element composite oxide contained in the positive electrode active material, specifically, lithium cobaltate (LiCoO 2 ), lithium nickelate (LiNiO 2 ), lithium manganate (LiMn 2 O 4 ), etc. Is mentioned. Among such positive electrode active materials, lithium manganate having a spinel structure that is inexpensive and excellent in safety is being used mainly, but improvement in high-temperature characteristics has been an issue. So far, a method of substituting a part of Mn with another element, a method of coating the surface of lithium manganate, etc. have been studied, but it is not always satisfactory in terms of the effect of improving the high temperature characteristics. There wasn't. On the other hand, a lithium secondary battery using a hybrid positive electrode active material in which lithium manganate and a layered compound are mixed has been disclosed, but it was not always satisfactory in terms of effects as well (patents) Reference 1).
JP 2003-168430 A

本発明は、上述の問題を解決するためになされたものであり、高温特性、特に高温保存特性に優れたリチウム二次電池を提供することを目的とする。   The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a lithium secondary battery excellent in high-temperature characteristics, particularly high-temperature storage characteristics.

上記目的を達成するため、本発明によれば、以下のリチウム二次電池が提供される。   In order to achieve the above object, according to the present invention, the following lithium secondary battery is provided.

［１］ 結晶系の異なる２種類以上のリチウム遷移金属酸化物を含有した、リチウムイオンの挿入・脱離が可能な正極活物質を備えたリチウム二次電池であって、２種類以上の前記リチウム遷移金属酸化物のうち、少なくとも１種類が、複数の互いに異なる相構造（異相構造）を有する複数相化合物であり、且つ、前記２種類以上の前記リチウム遷移金属酸化物のうち、別の１種類がスピネル構造を有するマンガン酸リチウムであり、前記複数相化合物が、層状構造を有し、前記複数相化合物の、Ｘ線回折法の走査範囲（２θ＝１０°〜７０°）における前記異相構造の最大ピーク強度を（ａ）とするとともに、前記複数相化合物の最大ピーク強度を（ｂ）としたときに、ＸＲＤピーク強度比（ａ／ｂ）が、０．００１〜０．４０であり、前記複数相化合物が、Ｍｎ及びＮｉを含有することを特徴とするリチウム二次電池。 [1] A lithium secondary battery comprising a positive electrode active material capable of inserting / extracting lithium ions, containing two or more types of lithium transition metal oxides having different crystal systems, wherein the two or more types of lithium At least one of the transition metal oxides is a multiple phase compound having a plurality of different phase structures (heterophase structures), and another one of the two or more types of the lithium transition metal oxides. Is a lithium manganate having a spinel structure, the multiphase compound has a layered structure, and the multiphase compound has a heterogeneous structure in the scanning range (2θ = 10 ° to 70 °) of the X-ray diffraction method. When the maximum peak intensity is (a) and the maximum peak intensity of the multiphase compound is (b), the XRD peak intensity ratio (a / b) is 0.001 to 0.40, Duplicate The lithium secondary battery, wherein the number phase compound contains Mn and Ni.

［２］ Ｍｎ及びＮｉを含有する前記複数相化合物が、一般式（Ｉ）ＬｉａＭ１ ＸＭｎＹＮｉ１−Ｘ−ＹＯ２±σ（Ｍ１はＭｎ以外の１種類以上の元素、ａは、０．１≦ａ≦１．３の範囲のＬｉ量、Ｘは０≦Ｘ≦０．５、Ｙは０＜Ｙ≦０．５の範囲の置換量、σは、０≦σ≦０．０５の範囲の酸素欠損量又は酸素過剰量をそれぞれ意味する）で示される前記［１］に記載のリチウム二次電池。 [ 2 ] The multi-phase compound containing Mn and Ni is represented by the general formula (I) Li a M 1 X Mn Y Ni 1-XY 2 + σ (M 1 is one or more elements other than Mn, a is the Li amount in the range of 0.1 ≦ a ≦ 1.3, X is 0 ≦ X ≦ 0.5, Y is the substitution amount in the range of 0 <Y ≦ 0.5, and σ is 0 ≦ σ ≦ The lithium secondary battery according to the above [ 1 ], which represents an oxygen deficiency amount or an oxygen excess amount in the range of 0.05.

［３］ Ｍｎ及びＮｉを含有する前記複数相化合物が、一般式（ＩＩ）ＬｉａＭ１ ＸＭｎ０．５Ｎｉ０．５−ＸＯ２±σ、又は一般式（ＩＩＩ）ＬｉａＭ１ ＸＭｎ０．５−ＸＮｉ０．５Ｏ２±σで示される前記［１］又は［２］に記載のリチウム二次電池。 [ 3 ] The multiphase compound containing Mn and Ni is represented by the general formula (II) Li a M 1 X Mn 0.5 Ni 0.5-X O 2 ± σ or the general formula (III) Li a M 1. The lithium secondary battery according to [1] or [2] , which is represented by X Mn 0.5-X Ni 0.5 O 2 ± σ .

［４］ Ｍｎ及びＮｉを含有する前記複数相化合物が、前記一般式（Ｉ）、一般式（ＩＩ）又は一般式（ＩＩＩ）における元素（Ｍ１）として、Ｔｉ、Ａｌ及びＢからなる群から選ばれる少なくとも一種を含有する前記［２］又は［３］に記載のリチウム二次電池。 [ 4 ] The multiphase compound containing Mn and Ni is selected from the group consisting of Ti, Al and B as the element (M 1 ) in the general formula (I), the general formula (II) or the general formula (III). The lithium secondary battery according to the above [ 2 ] or [ 3 ], which contains at least one selected.

［５］ Ｍｎ及びＮｉを含有する前記複数相化合物が、粒状であり、その一次粒子と前記一次粒子が集合した二次粒子とが混在する混合物の平均粒子径が５０μｍ以下で、比表面積が２．０ｍ２／ｇ以下である前記［１］〜［４］のいずれかに記載のリチウム二次電池。 [ 5 ] The multi-phase compound containing Mn and Ni is granular, the mixture of the primary particles and the secondary particles in which the primary particles are aggregated has an average particle diameter of 50 μm or less, and a specific surface area of 2 The lithium secondary battery according to any one of [1] to [ 4 ], which is 0.0 m 2 / g or less.

［６］ 前記複数相化合物の、前記正極活物質中における含有割合が、１０〜９０質量％である前記［１］〜［５］のいずれかに記載のリチウム二次電池。 [ 6 ] The lithium secondary battery according to any one of [1] to [ 5 ], wherein the content ratio of the multiphase compound in the positive electrode active material is 10 to 90 mass%.

［７］ 前記マンガン酸リチウムが、一般式（ＩＶ）ＬｉａＭ２ ＺＭｎ２−ＺＯ４±σ（Ｍ２はＭｎ以外の１種類以上の元素、ａは、０．１≦ａ≦１．３の範囲のＬｉ量、Ｚは０≦Ｚ≦０．５の範囲の置換量、σは、０≦σ≦０．０５の範囲の酸素欠損量又は酸素過剰量をそれぞれ意味する）で示される前記［１］〜［６］のいずれかに記載のリチウム二次電池。 [7] The lithium manganate is represented by the general formula (IV) Li a M 2 Z Mn 2-Z O 4 ± σ (M 2 is one or more elements other than Mn, a is, 0.1 ≦ a ≦ 1 .3 in the range, Z is the substitution amount in the range of 0 ≦ Z ≦ 0.5, and σ is the oxygen deficiency or oxygen excess in the range of 0 ≦ σ ≦ 0.05. The lithium secondary battery according to any one of [ 1 ] to [ 6 ].

［８］ 前記マンガン酸リチウムが、前記一般式（ＩＶ）ＬｉａＭ２ ＺＭｎ２−ＺＯ４±σにおける前記元素（Ｍ２）として、Ｌｉ、Ｆｅ、Ｎｉ、Ｍｇ、Ｚｎ、Ｃｏ、Ｃｒ、Ａｌ、Ｂ、Ｖ、Ｓｉ、Ｓｎ、Ｓｂ、Ｎｂ、Ｔａ、Ｍｏ、Ｔｉ及びＷからなる群から選ばれる少なくとも一種の元素を含有する前記［７］に記載のリチウム二次電池。 [8] The lithium manganate, wherein the general formula (IV) Li a M 2 Z Mn 2-Z O 4 wherein at ± sigma element (M 2), Li, Fe , Ni, Mg, Zn, Co, Cr , Al, B, V, Si, Sn, Sb, Nb, Ta, Mo, Ti, and the lithium secondary battery according to [ 7 ], containing at least one element selected from the group consisting of W and W.

［９］ 前記マンガン酸リチウムが、前記一般式（ＩＶ）ＬｉａＭ２ ＺＭｎ２−ＺＯ４±σにおける前記元素（Ｍ２）として、少なくともＬｉ、Ｎｉ及びＴｉを含有する前記［７］又は［８］に記載のリチウム二次電池。 [9] The lithium manganate, wherein the general formula (IV) Li a M 2 Z Mn 2-Z O 4 wherein at ± sigma element (M 2), said containing at least Li, Ni and Ti [7] Or the lithium secondary battery as described in [ 8 ].

［１０］ 前記マンガン酸リチウムが、粒状であり、その一次粒子の形状が八面体形で、前記一次粒子と前記一次粒子が集合した二次粒子とが混在する混合物の平均粒子径が５０μｍ以下で、比表面積が１．０ｍ２／ｇ以下である前記［７］〜［９］のいずれかに記載のリチウム二次電池。 [ 10 ] The lithium manganate is granular, the shape of the primary particles is octahedral, and the mixture of the primary particles and the secondary particles in which the primary particles are aggregated has an average particle diameter of 50 μm or less. The lithium secondary battery according to any one of [ 7 ] to [ 9 ], wherein the specific surface area is 1.0 m 2 / g or less.

［１１］ 前記マンガン酸リチウムの、前記正極活物質中における含有割合が、１０〜９０質量％である前記［７］〜［１０］のいずれかに記載のリチウム二次電池。 [ 11 ] The lithium secondary battery according to any one of [ 7 ] to [ 10 ], wherein a content ratio of the lithium manganate in the positive electrode active material is 10 to 90% by mass.

［１２］ 前記正極活物質に加えて負極活物質を備え、前記負極活物質が、人造黒鉛、天然黒鉛又はハードカーボンである前記［１］〜［１１］のいずれかに記載のリチウム二次電池。 [ 12 ] The lithium secondary battery according to any one of [1] to [ 11 ], further including a negative electrode active material in addition to the positive electrode active material, wherein the negative electrode active material is artificial graphite, natural graphite, or hard carbon. .

本発明によって、高温特性、特に高温保存特性に優れたリチウム二次電池が提供される。本発明のリチウム二次電池が高温特性、特に高温保存特性に優れたものとなるのは、正極活物質を構成するリチウム遷移金属酸化物のうちの複数相化合物の異なる相構造（異相構造）が、高温時におけるマンガン酸リチウムからのＭｎ溶出を抑制し、これがセルの高温特性を向上させるものと考えられる。このような効果は、同じような層状（相状）化合物であっても前述の特許文献１に開示されたような単相構造を有する単相構造化合物からでは期待することができない。また、一般に層状化合物は合成が難しく、原子レベルで原料を混合する必要があり、例えば、予め共沈化合物（例えば、Ｎｉ−Ｍｎの水酸化物）を合成し、Ｌｉ源の原料と混合・焼成して合成する。従って、合成工程が煩雑になり、正極活物質のコスト、延いてはセルのコストが高くなる。一方、本発明では複数の互いに異なる相構造を有する複数相化合物を使用するので、通常通りの固相合成を用いることができ、コストの低減化を図ることができる。   The present invention provides a lithium secondary battery excellent in high-temperature characteristics, particularly high-temperature storage characteristics. The lithium secondary battery of the present invention has excellent high-temperature characteristics, particularly high-temperature storage characteristics, because the different phase structures (heterophase structures) of the multiphase compounds among the lithium transition metal oxides constituting the positive electrode active material. It is considered that Mn elution from lithium manganate at high temperature is suppressed, which improves the high temperature characteristics of the cell. Such an effect cannot be expected from a single-phase structure compound having a single-phase structure as disclosed in Patent Document 1 described above even if it is a similar layered (phase-like) compound. In general, layered compounds are difficult to synthesize, and it is necessary to mix raw materials at the atomic level. For example, a coprecipitated compound (for example, Ni-Mn hydroxide) is synthesized in advance and mixed and fired with the Li source raw material. To synthesize. Therefore, the synthesis process becomes complicated, and the cost of the positive electrode active material and the cost of the cell increase accordingly. On the other hand, in the present invention, since a plurality of multiphase compounds having different phase structures are used, the usual solid phase synthesis can be used, and the cost can be reduced.

以下、本発明を実施するための最良の形態を具体的に説明する。   The best mode for carrying out the present invention will be specifically described below.

本発明のリチウム二次電池は、結晶系の異なる２種類以上のリチウム遷移金属酸化物を含有した、リチウムイオンの挿入・脱離が可能な正極活物質を備えたリチウム二次電池であって、２種類以上の前記リチウム遷移金属酸化物のうち、少なくとも１種類が、複数の互いに異なる相構造（異相構造）を有する複数相化合物であることを特徴とするものである。   The lithium secondary battery of the present invention is a lithium secondary battery comprising a positive electrode active material capable of inserting and removing lithium ions, containing two or more types of lithium transition metal oxides having different crystal systems, Of the two or more types of lithium transition metal oxides, at least one type is a multiphase compound having a plurality of mutually different phase structures (heterophase structures).

本発明のリチウム二次電池の電池構造としては特に制限はないが、例えば、板状に成形された正極活物質と負極活物質との間にセパレータを配して電解液を充填させたコイン型や、金属箔の表面に正極活物質を塗工してなる正極板と、同様に金属箔の表面に負極活物質を塗工してなる負極板とを、セパレータを介して捲回又は積層してなる電極体を用いた円筒型や箱型の各種電池を挙げることができる。   The battery structure of the lithium secondary battery of the present invention is not particularly limited. For example, a coin type in which a separator is disposed between a positive electrode active material and a negative electrode active material formed into a plate shape and filled with an electrolyte. Alternatively, a positive electrode plate formed by applying a positive electrode active material to the surface of a metal foil and a negative electrode plate formed by applying a negative electrode active material to the surface of the metal foil are wound or laminated via a separator. Cylindrical and box-type batteries using the electrode body can be mentioned.

本発明は、上述のように、正極活物質に含有される２種類以上のリチウム遷移金属酸化物のうち、少なくとも１種類が、複数の互いに異なる相構造（異相構造）を有する複数相化合物であることを特徴とするものである。このような複数相化合物としては、例えば、層状構造を有するリチウム遷移金属酸化物等を挙げることができる。このような層状構造を有するリチウム酸化物としては具体的には、リチウム・ニッケル・マンガン複合酸化物を挙げることができる。   As described above, the present invention is a multiphase compound in which at least one of two or more types of lithium transition metal oxides contained in the positive electrode active material has a plurality of mutually different phase structures (heterophase structures). It is characterized by this. Examples of such a multiphase compound include a lithium transition metal oxide having a layered structure. Specific examples of lithium oxides having such a layered structure include lithium / nickel / manganese composite oxides.

本発明においては、複数相化合物の、Ｘ線回折法の走査範囲（２θ＝１０°〜７０°）における異相構造の最大ピーク強度を（ａ）とするとともに、複数相化合物の最大ピーク強度を（ｂ）としたときに、ＸＲＤピーク強度比（ａ／ｂ）が、０．００１〜０．４０であることが好ましく、０．００１〜０．３がさらに好ましく、０．０１〜０．２が特に好ましい。０．０００１未満であると、効果が認められないことがあり、０．４０を超えると、異相による悪影響が生じることがある。   In the present invention, the maximum peak intensity of the heterophasic structure in the X-ray diffraction scanning range (2θ = 10 ° to 70 °) of the multiphase compound is (a), and the maximum peak intensity of the multiphase compound is ( When b), the XRD peak intensity ratio (a / b) is preferably 0.001 to 0.40, more preferably 0.001 to 0.3, and 0.01 to 0.2. Particularly preferred. If it is less than 0.0001, the effect may not be recognized, and if it exceeds 0.40, adverse effects due to different phases may occur.

複数相化合物は、Ｍｎを含有することが合成のし易さの面から好ましい。   The multiphase compound preferably contains Mn from the viewpoint of ease of synthesis.

複数相化合物は、Ｍｎ及びＮｉを含有することが結晶構造の安定化の面から好ましい。   The multiphase compound preferably contains Mn and Ni from the viewpoint of stabilization of the crystal structure.

Ｍｎ及びＮｉを含有する複数相化合物は、一般式（Ｉ）ＬｉａＭ１ ＸＭｎＹＮｉ１−Ｘ−ＹＯ２±σ （Ｍ１はＭｎ以外の１種類以上の元素、ａは、０．１≦ａ≦１．３の範囲のＬｉ量、Ｘは０≦Ｘ≦０．５、Ｙは０＜Ｙ≦０．５の範囲の置換量、σは、０≦σ≦０．０５の範囲の酸素欠損量又は酸素過剰量をそれぞれ意味する）で示されるものであることが好ましい。置換量（Ｘ）が０．５を超えると、複数相化合物の容量が小さくなるばかりでなく、結晶構造に歪みが生じ易くなり、逆に充放電サイクル特性に悪影響を及ぼすことがあり、置換量（Ｙ）が０．５を超えると、前述の置換量（Ｘ）の場合と同様のことが生じることがある。 The multiphase compound containing Mn and Ni has the general formula (I) Li a M 1 X Mn Y Ni 1-XY 2 + σ (M 1 is one or more elements other than Mn, a is 0 .1 ≦ a ≦ 1.3 Li amount, X is 0 ≦ X ≦ 0.5, Y is substitution amount in the range of 0 <Y ≦ 0.5, and σ is 0 ≦ σ ≦ 0.05. It is preferable that the oxygen deficiency or oxygen excess in the range is indicated. When the substitution amount (X) exceeds 0.5, not only the capacity of the multiphase compound is reduced, but also the crystal structure is likely to be distorted, which may adversely affect the charge / discharge cycle characteristics. When (Y) exceeds 0.5, the same thing as the case of the above-mentioned substitution amount (X) may occur.

Ｍｎ及びＮｉを含有する複数相化合物は、一般式（ＩＩ）ＬｉａＭ１ ＸＭｎ０．５Ｎｉ０．５−ＸＯ２±σ 、又は一般式（ＩＩＩ）ＬｉａＭ１ ＸＭｎ０．５−ＸＮｉ０．５Ｏ２±σ で示されるものであることがさらに好ましい。 The multiphase compound containing Mn and Ni has a general formula (II) Li a M 1 X Mn 0.5 Ni 0.5-X O 2 ± σ or a general formula (III) Li a M 1 X Mn 0. More preferably, it is represented by 5-X Ni 0.5 O 2 ± σ .

Ｍｎ及びＮｉを含有する複数相化合物は、一般式（Ｉ）、一般式（ＩＩ）又は一般式（ＩＩＩ）における元素（Ｍ1）として、Ｔｉ、Ａｌ及びＢからなる群から選ばれる少なくとも一種を含有することが結晶構造の安定化から好ましい。 The multiphase compound containing Mn and Ni contains at least one selected from the group consisting of Ti, Al, and B as the element (M 1 ) in the general formula (I), general formula (II), or general formula (III). It is preferable to contain it from the stabilization of the crystal structure.

Ｍｎ及びＮｉを含有する複数相化合物は、粒状であり、その一次粒子と一次粒子が集合した二次粒子とが混在する混合物の平均粒子径が５０μｍ以下で、比表面積が２．０ｍ2／ｇ以下であることが電極シートの製造のし易さの面から好ましい。平均粒子径が５０μｍを超えると、粒子内でのＬｉ+イオンの拡散抵抗が大きくなり、層状化合物自体の抵抗が大きくなるとともに、電池にした場合に内部抵抗が大きくなることがある。また、電極板が作り難くなることがある。比表面積が２．０ｍ2／ｇを超えると、粒子間の接触抵抗が大きくなり、層状化合物自体の抵抗が大きくなるととともに、電池にした場合に内部抵抗が大きくなることがある。 The multiphase compound containing Mn and Ni is granular, and the average particle diameter of the mixture in which the primary particles and the secondary particles in which the primary particles are aggregated is 50 μm or less and the specific surface area is 2.0 m 2 / g. The following is preferable from the viewpoint of ease of production of the electrode sheet. When the average particle diameter exceeds 50 μm, the diffusion resistance of Li + ions in the particles increases, the resistance of the layered compound itself increases, and the internal resistance may increase in the case of a battery. Also, it may be difficult to make an electrode plate. When the specific surface area exceeds 2.0 m 2 / g, the contact resistance between the particles increases, the resistance of the layered compound itself increases, and the internal resistance may increase when used in a battery.

複数相化合物の、正極活物質中における含有割合は、１０〜９０質量％であることが好ましく、２０〜８０質量％であることがさらに好ましく、３０〜７０質量％であることが特に好ましい。１０質量％未満であると、複数相化合物の混合効果がなくなることがあり、９０質量％を超えると、複数相化合物の特徴が強く発現し、電池の内部抵抗が大きくなる傾向がある。   The content ratio of the multiphase compound in the positive electrode active material is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, and particularly preferably 30 to 70% by mass. If it is less than 10% by mass, the mixing effect of the multiphase compound may be lost, and if it exceeds 90% by mass, the characteristics of the multiphase compound are strongly expressed and the internal resistance of the battery tends to increase.

本発明においては、正極活物質に含有される２種類以上のリチウム遷移金属酸化物のうち、少なくとも１種類がスピネル構造を有するマンガン酸リチウムであることが好ましい。このように構成することによって、高温特性、特に高温保存特性に優れた正極活物質を得ることができる。   In the present invention, it is preferable that at least one of lithium transition metal oxides contained in the positive electrode active material is a lithium manganate having a spinel structure. By comprising in this way, the positive electrode active material excellent in the high temperature characteristic, especially high temperature storage characteristic can be obtained.

マンガン酸リチウムは、一般式（ＩＶ）ＬｉａＭ２ ＺＭｎ２−ＺＯ４±σ （Ｍ２はＭｎ以外の１種類以上の元素、ａは、０．１≦ａ≦１．３の範囲のＬｉ量、Ｚは０≦Ｚ≦０．５の範囲の置換量、σは、０≦σ≦０．０５の範囲の酸素欠損量又は酸素過剰量をそれぞれ意味する）で示されるものであることが好ましい。置換量（Ｚ）が０．５を超えると、マンガン酸リチウムの正極活物質としての容量が大きく減少するために、電池容量も大きく減少することがある。 Lithium manganate has the general formula (IV) Li a M 2 Z Mn 2 —Z O 4 ± σ (M 2 is one or more elements other than Mn, a is in the range of 0.1 ≦ a ≦ 1.3 Li, Z is a substitution amount in the range of 0 ≦ Z ≦ 0.5, and σ is an oxygen deficiency amount or an oxygen excess amount in the range of 0 ≦ σ ≦ 0.05, respectively. It is preferable. When the amount of substitution (Z) exceeds 0.5, the capacity of the lithium manganate as the positive electrode active material is greatly reduced, so that the battery capacity may be greatly reduced.

マンガン酸リチウムは、上述の一般式（ＩＶ）ＬｉａＭ２ ＺＭｎ２−ＺＯ４±σ における前記元素（Ｍ２）として、Ｌｉ、Ｆｅ、Ｎｉ、Ｍｇ、Ｚｎ、Ｃｏ、Ｃｒ、Ａｌ、Ｂ、Ｖ、Ｓｉ、Ｓｎ、Ｓｂ、Ｎｂ、Ｔａ、Ｍｏ、Ｔｉ及びＷからなる群から選ばれる少なくとも一種の元素を含有することが好ましい。このように構成することによって、マンガン酸リチウムの結晶構造を安定化することができる。 Lithium manganate is Li, Fe, Ni, Mg, Zn, Co, Cr, Al, as the element (M 2 ) in the above general formula (IV) Li a M 2 Z Mn 2 —Z O 4 ± σ . It is preferable to contain at least one element selected from the group consisting of B, V, Si, Sn, Sb, Nb, Ta, Mo, Ti and W. By comprising in this way, the crystal structure of lithium manganate can be stabilized.

マンガン酸リチウムは、上述の一般式（ＩＶ）ＬｉａＭ２ ＺＭｎ２−ＺＯ４±σ における前記元素（Ｍ２）として、少なくともＬｉ、Ｎｉ及びＴｉを含有することが好ましい。このように構成することによって、マンガン酸リチウムの結晶構造をより安定化することができる。 The lithium manganate preferably contains at least Li, Ni, and Ti as the element (M 2 ) in the above general formula (IV) Li a M 2 Z Mn 2 —Z O 4 ± σ . By comprising in this way, the crystal structure of lithium manganate can be stabilized more.

マンガン酸リチウムは、粒状であり、その一次粒子の形状が八面体形で、一次粒子と一次粒子が集合した二次粒子とが混在する混合物の平均粒子径が５０μｍ以下で、比表面積が１．０ｍ2／ｇ以下であることが好ましい。マンガン酸リチウムのモルフォロジーとしては、一次粒子が八面体形を有することが好ましいが、これは、結晶性の一つの尺度であり、マンガン酸リチウムの単結晶が八面体形を有するように、組成の均一化を示すことになる。また、平均粒子径を超えると、粒子内でのＬｉ+イオンの拡散抵抗が大きくなり、マンガン酸リチウム自体の抵抗が大きくなるとともに、電池にした場合に内部抵抗が大きくなることがある。また、電極板が作り難くなることがある。一方、比表面積が１．０ｍ2／ｇを超えると、Ｍｎ溶出量が大きくなり、混合による効果が減少することがある。 Lithium manganate is granular, the shape of primary particles is octahedral, the mixture of primary particles and secondary particles in which primary particles are aggregated has an average particle size of 50 μm or less, and a specific surface area of 1. It is preferably 0 m 2 / g or less. The morphology of the lithium manganate is preferably such that the primary particles have an octahedral shape, but this is one measure of crystallinity and the composition of the lithium manganate single crystal has an octahedral shape. It will show uniformity. When the average particle diameter is exceeded, the diffusion resistance of Li + ions in the particles increases, the resistance of lithium manganate itself increases, and the internal resistance may increase in the case of a battery. Also, it may be difficult to make an electrode plate. On the other hand, when the specific surface area exceeds 1.0 m 2 / g, the Mn elution amount increases and the effect of mixing may decrease.

マンガン酸リチウムの、正極活物質中における含有割合が、１０〜９０質量％であることが好ましく、２０〜８０質量％であることがさらに好ましく、３０〜７０質量％であることが特に好ましい。１０質量％未満であると、電池の内部抵抗が大きくなる傾向があり、９０質量％を超えると、電池の高温特性向上がみられないことがある。   The content ratio of lithium manganate in the positive electrode active material is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, and particularly preferably 30 to 70% by mass. If the content is less than 10% by mass, the internal resistance of the battery tends to increase. If the content exceeds 90% by mass, the high-temperature characteristics of the battery may not be improved.

本発明のリチウム二次電池を構成するための他の部材（材料）としては、従来公知の種々の材料を用いることができる。例えば、負極活物質としては、ソフトカーボン、ハードカーボン等のアモルファス系炭素質材料；人造黒鉛、天然黒鉛等の高黒鉛化炭素材料を適宜選択して用いることができる。中でも、リチウム容量の大きい高黒鉛化炭素材料を用いることが好ましい。   As other members (materials) for constituting the lithium secondary battery of the present invention, various conventionally known materials can be used. For example, as the negative electrode active material, amorphous carbonaceous materials such as soft carbon and hard carbon; and highly graphitized carbon materials such as artificial graphite and natural graphite can be appropriately selected and used. Among them, it is preferable to use a highly graphitized carbon material having a large lithium capacity.

非水電解液に用いられる有機溶媒としては、エチレンカーボネート（ＥＣ）、ジエチルカーボネート（ＤＥＣ）、ジメチルカーボネート（ＤＭＣ）、プロピレンカーボネート（ＰＣ）等の炭酸エステル系溶媒；γ−ブチロラクトン；テトラヒドロフラン；アセトニトリル等の単独溶媒又は混合溶媒が好適に用いられる。   Examples of the organic solvent used for the non-aqueous electrolyte include carbonate solvents such as ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and propylene carbonate (PC); γ-butyrolactone; tetrahydrofuran; acetonitrile and the like These single solvents or mixed solvents are preferably used.

電解質としては、六フッ化リン酸リチウム（ＬｉＰＦ6）、ホウフッ化リチウム（ＬｉＢＦ４4）等のリチウム錯体フッ素化合物；過塩素酸リチウム（ＬｉＣｌＯ4）等のリチウムハロゲン化物；リチウムビス（オキサラト）ボレート（ＬｉＢＯＢ）等を挙げることができ、１種類又は２種類以上を上述の溶媒に溶解して用いることができる。特に、酸化分解が起こり難く、非水電解液の導電性の高いＬｉＰＦ6を用いることが好ましい。 Examples of the electrolyte include lithium complex fluorine compounds such as lithium hexafluorophosphate (LiPF 6 ) and lithium borofluoride (LiBF 4 4 ); lithium halides such as lithium perchlorate (LiClO 4 ); lithium bis (oxalato) borate ( LiBOB) and the like can be used, and one type or two or more types can be dissolved in the above solvent and used. In particular, it is preferable to use LiPF 6 which does not easily undergo oxidative decomposition and has a high conductivity of the non-aqueous electrolyte.

（実施例１〜３６、比較例１〜７）
（マンガン酸リチウムの合成）
出発原料として、市販のＬｉ２ＣＯ３、ＭｎＯ２粉末を用い、ＬｉＭｎ２Ｏ４の組成となるようにそれぞれ秤量し、混合した。次いで、酸化雰囲気中、８００℃、２４時間の焼成を行い、スピネル構造を有するマンガン酸リチウムを合成した。上述の一般式（ＩＶ）ＬｉａＭ２ ＺＭｎ２−ＺＯ４±σ （Ｍ２はマンガン以外の１種以上の元素）における元素（置換元素）（Ｍ２）としては、以下に示すものを用いた。周期率表ＶＩＩＩ族に属するＮｉ、Ｆｅ、ＣｏについてはＮｉを、周期率表ＶＩＢ族に属するＣｒ、Ｍｏ、ＷについてはＣｒを代表種として、周期率表ＩＩＩＡ族に属するＡｌ、ＢについてはＡｌを代表種として、周期率表ＶＢ族に属するＶ、Ｎｂ、ＴａについてはＶを代表種として、周期率表ＩＶＡ族に属するＳｉ、ＳｎについてはＳｎを代表種として用い、それ以外の置換元素にはＬｉ、Ｍｇ、Ｚｎ、Ｔｉ、を用いた。これらにより、前述の出発原料以外に、ＮｉＯ粉末を用いてＬｉＭｎ１．９Ｎｉ０．１Ｏ４、ＭｇＯ粉末を用いてＬｉＭｎ１．９Ｍｇ０．１Ｏ４、ＺｎＯ粉末を用いてＬｉＭｎ１．９Ｚｎ０．１Ｏ４、Ｃｒ３Ｏ４を用いてＬｉＭｎ１．９Ｃｒ０．１Ｏ４、Ａｌ２Ｏ３を用いてＬｉＭｎ１．９Ａｌ０．１Ｏ４、Ｖ２Ｏ５を用いてＬｉＭｎ１．９Ｖ０．１Ｏ４、ＳｎＯ２を用いてＬｉＭｎ１．９Ｓｎ０．１Ｏ４、ＴｉＯ２を用いてＬｉＭｎ１．９Ｔｉ０．１Ｏ４の組成となるように同様の条件でそれぞれ合成した。また、Ｌｉ１．１Ｎｉ０．５Ｔｉ０．５Ｍｎ１．８Ｏ４についても合成した。 (Examples 1-36, Comparative Examples 1-7)
(Synthesis of lithium manganate)
As starting materials, commercially available Li 2 CO 3 and MnO 2 powders were weighed and mixed so as to have a composition of LiMn 2 O 4 . Next, baking was performed in an oxidizing atmosphere at 800 ° C. for 24 hours to synthesize lithium manganate having a spinel structure. The element (substitution element) (M 2 ) in the above general formula (IV) Li a M 2 Z Mn 2 —Z O 4 ± σ (M 2 is one or more elements other than manganese) is shown below. Was used. For Ni, Fe, and Co belonging to the periodic table VIII group, Ni is used as a representative species for Cr, Mo, and W belonging to the periodic table VI group B , and Al and B belonging to the periodic table III group A representative species are Al, V belonging to periodic table V B group, Nb, as a representative species V for Ta, using Si belonging to periodic table IV a group, the Sn for Sn as a representative species, otherwise Li, Mg, Zn, and Ti were used as substitution elements. As a result, in addition to the starting materials described above, LiMn 1.9 Ni 0.1 O 4 using NiO powder, LiMn 1.9 Mg 0.1 O 4 using MgO powder, LiMn 1 using ZnO powder . 9 Zn 0.1 O 4 , Cr 3 O 4 is used, LiMn 1.9 Cr 0.1 O 4 , Al 2 O 3 is used, LiMn 1.9 Al 0.1 O 4 , V 2 O 5 is used LiMn 1.9 V 0.1 O 4 , SnO 2 is used to make LiMn 1.9 Sn 0.1 O 4 , TiO 2 is used to make the composition LiMn 1.9 Ti 0.1 O 4 Each was synthesized under the conditions of Li 1.1 Ni 0.5 Ti 0.5 Mn 1.8 O 4 was also synthesized.

複数相化合物（異相構造を含むＭｎ−Ｎｉ系層状化合物）の合成）
出発原料として、市販のＬｉ2ＣＯ3、ＭｎＯ2、ＮｉＯ粉末を用い、ＬｉＭｎ0.5Ｎｉ0.5Ｏ2の組成となるように予め秤量し、混合した。次いで、酸化雰囲気中、１０００℃、２４時間の焼成を行い、Ｎｉ−Ｍｎ系層状化合物を合成した。また、異相構造を含ませるために、原料の混合時間を１分間、１０分間、２０分間、３０分間、６０分間、１２０分間、１５０分間として、以後は同様の焼成条件で合成した。異相構造の存在、割合については粉末Ｘ線回折法（以下、「ＸＲＤ分析」ということがある）を用いて測定した。また、上記以外の元素を添加し、同様に合成した。周期率表ＶＩＩＩ族に属するＦｅ、ＣｏについてはＣｏを、周期率表ＩＩＩA族に属するＡｌ、ＢについてはＡｌを代表種として、それ以外の置換元素にはＴｉ、を用いた。その際、これらの原料として、Ｃｏ3Ｏ4粉末、Ａｌ2Ｏ3粉末、ＴｉＯ2粉末を用いた。 Multi-phase compound (synthesis of Mn-Ni layered compound containing heterophase structure)
Commercially available Li 2 CO 3 , MnO 2 , and NiO powder were used as starting materials, and weighed and mixed in advance so as to have a composition of LiMn 0.5 Ni 0.5 O 2 . Next, firing was performed in an oxidizing atmosphere at 1000 ° C. for 24 hours to synthesize a Ni—Mn-based layered compound. Further, in order to include a heterogeneous structure, the raw materials were mixed for 1 minute, 10 minutes, 20 minutes, 30 minutes, 60 minutes, 120 minutes, and 150 minutes, and thereafter synthesized under the same firing conditions. The presence and ratio of the heterogeneous structure was measured using a powder X-ray diffraction method (hereinafter sometimes referred to as “XRD analysis”). Further, elements other than the above were added and synthesized in the same manner. For Fe and Co belonging to the periodic table VIII group, Co was used, for Al and B and B belonging to the periodic table III group A , Al was used as a representative species, and Ti was used as the other substitution element. At that time, Co 3 O 4 powder, Al 2 O 3 powder, and TiO 2 powder were used as these raw materials.

（異相構造の混合割合の測定）
Ｍｎ−Ｎｉ系層状化合物に含まれる異相構造については、ＸＲＤ分析により混合割合を調べた。理学電機製の粉末Ｘ線回折装置ＲＡＤ−ＩＢを使用して、表１に示した条件にて行った。なお、その実験手順は通常の手法を用いた。なお、走査範囲は２θ＝１０°〜７０°として、ＸＲＤピークの強度を、ＣＰＳ（Ｃｏｕｎｔｓ ｐｅｒ ｓｅｃｏｎｄ）で測定した。前述のＭｎ−Ｎｉ系層状化合物については最大の強度をもつＸＲＤピークが２θ＝１８°付近に出現し、異相構造については最大の強度をもつＸＲＤピークが２θ＝４３°付近に出現した。前者のＸＲＤピーク強度を（ｂ）として、後者のＸＲＤピーク強度を（ａ）として、そのピーク強度比（ａ／ｂ）を算出した。これらの手法により、原料混合時間とピーク強度比の関係（ａ／ｂ）を表２に示す。 (Measurement of mixing ratio of heterogeneous structure)
About the heterophasic structure contained in a Mn-Ni-type layered compound, the mixing ratio was investigated by XRD analysis. Using a powder X-ray diffractometer RAD-IB manufactured by Rigaku Corporation, the conditions shown in Table 1 were used. The experimental procedure used a normal method. The scanning range was 2θ = 10 ° to 70 °, and the intensity of the XRD peak was measured by CPS (Counts per second). For the Mn—Ni-based layered compound described above, the XRD peak having the maximum intensity appeared near 2θ = 18 °, and for the heterophase structure, the XRD peak having the maximum intensity appeared near 2θ = 43 °. The peak intensity ratio (a / b) was calculated with the former XRD peak intensity as (b) and the latter XRD peak intensity as (a). Table 2 shows the relationship (a / b) between the raw material mixing time and the peak intensity ratio by these methods.

Figure 0004954481
Figure 0004954481

Figure 0004954481
Figure 0004954481

（正極活物質の調製）
合成したマンガン酸リチウムと異相を含むＭｎ−Ｎｉ系層状化合物を表３〜７に示す割合（質量％）となるように乾式混合して、正極活物質を調製した。 (Preparation of positive electrode active material)
A positive electrode active material was prepared by dry-mixing the synthesized lithium manganate and the Mn—Ni-based layered compound containing a different phase so as to have the ratios (mass%) shown in Tables 3-7.

（電池の作製）
前述の正極材料（計４３サンプル）を使用し、導電材たるアセチレンブラック粉末と結着材たるポリフッ化ビニリデンを、質量比で７０：２５：５で添加・混合した。得られた混合物を３００ｋｇ／ｃｍ2の圧力で直径１０ｍｍφの円板状にプレス成形して正極とした。次に、ＥＣとＤＥＣが等体積比（１：１）で混合された有機溶媒に電解質としてＬｉＰＦ6を１ｍｏｌ／Ｌの濃度となるように溶解して調製した電解液、人造黒鉛又はハードカーボンからなる負極、正極及び負極を隔離するセパレータ、並びに前述のようにして作製した正極を用いてコインセルを作製した。 (Production of battery)
Using the above positive electrode material (43 samples in total), acetylene black powder as a conductive material and polyvinylidene fluoride as a binder were added and mixed at a mass ratio of 70: 25: 5. The obtained mixture was press-molded into a disk shape having a diameter of 10 mmφ at a pressure of 300 kg / cm 2 to obtain a positive electrode. Next, from an electrolytic solution prepared by dissolving LiPF 6 as an electrolyte in an organic solvent in which EC and DEC are mixed at an equal volume ratio (1: 1) to a concentration of 1 mol / L, artificial graphite or hard carbon A coin cell was manufactured using the negative electrode, the separator separating the positive electrode and the negative electrode, and the positive electrode manufactured as described above.

（セルの高温保存特性の評価）
次に、実施例と同じ要領で作製した４３個のコインセル（負極は人造黒鉛を使用）を室温１Ｃ電流レートで４．１Ｖまで充電、３．０Ｖまで放電のサイクルを１サイクルして、計３サイクルの充放電を行った（この時の３サイクル目の放電容量を（Ｐ）とする）。その後、さらに同じく１Ｃ電流レートで４．１Ｖまで充電し、内温６０℃に設定した恒温槽内に１２８ｈ設置した。６０℃保存後、コインセルを恒温槽から取出して、室温、１Ｃ電流レートで３．０Ｖまで放電、４．１Ｖまで充電、３．０Ｖまで放電（この時の放電容量を（Ｑ）とする）を行った。これにより、放電容量維持率（％）＝Ｑ／Ｐを求めた。結果を表３〜７に示す。表３から、Ｎｉ−Ｍｎ系層状化合物に含まれる異相構造の割合は、ＸＲＤピーク強度比が０．００１〜０．４０であることが好ましく、さらに好ましくは０．００１〜０．３、特に好ましくは０．０１〜０．２であることがわかる。 (Evaluation of high-temperature storage characteristics of cells)
Next, 43 coin cells prepared in the same manner as in the example (artificial graphite was used for the negative electrode) were charged to 4.1 V at a room temperature 1 C current rate and discharged to 3.0 V for one cycle, for a total of 3 The cycle was charged and discharged (the discharge capacity in the third cycle at this time is defined as (P)). Thereafter, the battery was further charged to 4.1 V at a 1 C current rate, and installed in a thermostat set at an internal temperature of 60 ° C. for 128 hours. After storage at 60 ° C., the coin cell is taken out of the thermostat, discharged to 3.0 V at room temperature and 1 C current rate, charged to 4.1 V, discharged to 3.0 V (the discharge capacity at this time is defined as (Q)). went. Thereby, the discharge capacity retention ratio (%) = Q / P was determined. The results are shown in Tables 3-7. From Table 3, the ratio of the heterophase structure contained in the Ni—Mn layered compound is preferably such that the XRD peak intensity ratio is 0.001 to 0.40, more preferably 0.001 to 0.3, and particularly preferably. Is found to be 0.01-0.2.

表４から、複数相化合物（異相構造を含むＮｉ−Ｍｎ系層状化合物）の、正極活物質中における含有割合が、１０〜９０質量％であることが好ましく、２０〜８０質量％であることがさらに好ましく、３０〜７０質量％であることが特に好ましいことがわかる。   From Table 4, it is preferable that the content rate in a positive electrode active material of a multiphase compound (Ni-Mn type | system | group layered compound containing a different phase structure) is 10-90 mass%, and it is 20-80 mass%. It is further preferred that it is particularly preferably 30 to 70% by mass.

表５、６から、マンガン酸リチウムについては、Ｌｉ、Ｆｅ、Ｎｉ、Ｍｇ、Ｚｎ、Ｃｏ、Ｃｒ、Ａｌ、Ｂ、Ｖ、Ｓｉ、Ｓｎ、Ｓｂ、Ｎｂ、Ｔａ、Ｍｏ、ｉ及びＷからなる群から選ばれる少なくとも一種の元素でＭｎの一部を置換した方が高温保存特性に向上がみられることがわかった。また、異相構造を含むＮｉ−Ｍｎ系層状化合物については、Ｔｉ、Ａｌ及びＢのうちのいずれかを含有する方が高温保存特性に向上がみられることがわかった。その理由として、マンガン酸リチウムの場合、置換により結晶構造がより安定化したためと考えられる。表７から、マンガン酸リチウムのＭｎ置換量については０≦Ｘ（置換量）≦０．５が好ましく、さらに好ましくは０≦Ｘ（置換量）≦０．３であることがわかった。   From Tables 5 and 6, for lithium manganate, the group consisting of Li, Fe, Ni, Mg, Zn, Co, Cr, Al, B, V, Si, Sn, Sb, Nb, Ta, Mo, i and W It was found that the high temperature storage characteristics were improved by substituting a part of Mn with at least one element selected from Moreover, about the Ni-Mn type | system | group layered compound containing a different phase structure, it turned out that the direction which contains any of Ti, Al, and B improves the high temperature storage characteristic. The reason is considered to be that the crystal structure was further stabilized by substitution in the case of lithium manganate. From Table 7, it was found that 0 ≦ X (substitution amount) ≦ 0.5 was preferable for the Mn substitution amount of lithium manganate, and more preferably 0 ≦ X (substitution amount) ≦ 0.3.

表８に、負極活物質のみを人造黒鉛からハードカーボンに代えた場合の容量維持率を示す。表８に示すように、表４と比較して容量維持率が高くなり、ハードカーボンの方が、高温保存特性がよりよくなることがわかった。

Figure 0004954481
Table 8 shows capacity retention rates when only the negative electrode active material is changed from artificial graphite to hard carbon. As shown in Table 8, it was found that the capacity retention rate was higher than in Table 4, and that the hard carbon had better high-temperature storage characteristics.
Figure 0004954481

Figure 0004954481
Figure 0004954481

Figure 0004954481
Figure 0004954481

Figure 0004954481
Figure 0004954481

Figure 0004954481
Figure 0004954481

Figure 0004954481
Figure 0004954481

本発明のリチウム二次電池は、ハイブリッド自動車、電気機器、通信機器等の駆動用電池として有効に用いられる。   The lithium secondary battery of the present invention is effectively used as a driving battery for hybrid vehicles, electrical devices, communication devices, and the like.

Claims (12)

結晶系の異なる２種類以上のリチウム遷移金属酸化物を含有した、リチウムイオンの挿入・脱離が可能な正極活物質を備えたリチウム二次電池であって、
２種類以上の前記リチウム遷移金属酸化物のうち、少なくとも１種類が、複数の互いに異なる相構造（異相構造）を有する複数相化合物であり、且つ、前記２種類以上の前記リチウム遷移金属酸化物のうち、別の１種類がスピネル構造を有するマンガン酸リチウムであり、
前記複数相化合物が、層状構造を有し、
前記複数相化合物の、Ｘ線回折法の走査範囲（２θ＝１０°〜７０°）における前記異相構造の最大ピーク強度を（ａ）とするとともに、前記複数相化合物の最大ピーク強度を（ｂ）としたときに、ＸＲＤピーク強度比（ａ／ｂ）が、０．００１〜０．４０であり、
前記複数相化合物が、Ｍｎ及びＮｉを含有することを特徴とするリチウム二次電池。 A lithium secondary battery comprising a positive electrode active material capable of inserting and removing lithium ions, comprising two or more types of lithium transition metal oxides having different crystal systems,
Of the two or more types of lithium transition metal oxides, at least one type is a multiphase compound having a plurality of different phase structures (heterophase structures), and the two or more types of lithium transition metal oxides One of them is lithium manganate having a spinel structure,
The multiphase compound has a layered structure;
The maximum peak intensity of the heterophase structure in the X-ray diffraction scanning range (2θ = 10 ° to 70 °) of the multiphase compound is (a), and the maximum peak intensity of the multiphase compound is (b). XRD peak intensity ratio (a / b) is 0.001 to 0.40,
The lithium secondary battery, wherein the multi-phase compound contains Mn and Ni. Ｍｎ及びＮｉを含有する前記複数相化合物が、一般式（Ｉ）ＬｉａＭ１ ＸＭｎＹＮｉ１−Ｘ−ＹＯ２±σ（Ｍ１はＭｎ以外の１種類以上の元素、ａは、０．１≦ａ≦１．３の範囲のＬｉ量、Ｘは０≦Ｘ≦０．５、Ｙは０＜Ｙ≦０．５の範囲の置換量、σは、０≦σ≦０．０５の範囲の酸素欠損量又は酸素過剰量をそれぞれ意味する）で示される請求項１に記載のリチウム二次電池。 The multi-phase compound containing Mn and Ni has the general formula (I) Li a M 1 X Mn Y Ni 1-XY 2 + σ (M 1 is one or more elements other than Mn, a is Li amount in the range of 0.1 ≦ a ≦ 1.3, X is 0 ≦ X ≦ 0.5, Y is the substitution amount in the range of 0 <Y ≦ 0.5, and σ is 0 ≦ σ ≦ 0.05 The lithium secondary battery according to claim 1, which is represented by an oxygen deficiency amount or an oxygen excess amount in the range of Ｍｎ及びＮｉを含有する前記複数相化合物が、一般式（ＩＩ）ＬｉａＭ１ ＸＭｎ０．５Ｎｉ０．５−ＸＯ２±σ、又は一般式（ＩＩＩ）ＬｉａＭ１ ＸＭｎ０．５−ＸＮｉ０．５Ｏ２±σで示される請求項１又は２に記載のリチウム二次電池。 The multiphase compound containing Mn and Ni is represented by the general formula (II) Li a M 1 X Mn 0.5 Ni 0.5-X O 2 ± σ or the general formula (III) Li a M 1 X Mn 0. the lithium secondary battery according to claim 1 or 2 represented by .5-X Ni 0.5 O 2 ± σ. Ｍｎ及びＮｉを含有する前記複数相化合物が、前記一般式（Ｉ）、一般式（ＩＩ）又は一般式（ＩＩＩ）における元素（Ｍ１）として、Ｔｉ、Ａｌ及びＢからなる群から選ばれる少なくとも一種を含有する請求項２又は３に記載のリチウム二次電池。 The multiphase compound containing Mn and Ni is at least selected from the group consisting of Ti, Al, and B as the element (M 1 ) in the general formula (I), the general formula (II), or the general formula (III). The lithium secondary battery according to claim 2 or 3 containing one kind. Ｍｎ及びＮｉを含有する前記複数相化合物が、粒状であり、その一次粒子と前記一次粒子が集合した二次粒子とが混在する混合物の平均粒子径が５０μｍ以下で、比表面積が２．０ｍ２／ｇ以下である請求項１〜４のいずれかに記載のリチウム二次電池。 The multi-phase compound containing Mn and Ni is granular, and the average particle size of the mixture in which the primary particles and the secondary particles in which the primary particles are aggregated is 50 μm or less, and the specific surface area is 2.0 m 2. The lithium secondary battery according to any one of claims 1 to 4 , which is / g or less. 前記複数相化合物の、前記正極活物質中における含有割合が、１０〜９０質量％である請求項１〜５のいずれかに記載のリチウム二次電池。 It said plurality phase compounds, the content in the positive electrode active material in the lithium secondary battery according to any one of claims 1 to 5 which is 10 to 90 mass%. 前記マンガン酸リチウムが、一般式（ＩＶ）ＬｉａＭ２ ＺＭｎ２−ＺＯ４±σ（Ｍ２はＭｎ以外の１種類以上の元素、ａは、０．１≦ａ≦１．３の範囲のＬｉ量、Ｚは０≦Ｚ≦０．５の範囲の置換量、σは、０≦σ≦０．０５の範囲の酸素欠損量又は酸素過剰量をそれぞれ意味する）で示される請求項１〜６のいずれかに記載のリチウム二次電池。 The lithium manganate has the general formula (IV) Li a M 2 Z Mn 2 —Z O 4 ± σ (M 2 is one or more elements other than Mn, a is 0.1 ≦ a ≦ 1.3 The Li amount in the range, Z is the substitution amount in the range of 0 ≦ Z ≦ 0.5, and σ means the oxygen deficiency amount or the oxygen excess amount in the range of 0 ≦ σ ≦ 0.05, respectively. The lithium secondary battery according to any one of 1 to 6 . 前記マンガン酸リチウムが、前記一般式（ＩＶ）ＬｉａＭ２ ＺＭｎ２−ＺＯ４±σにおける前記元素（Ｍ２）として、Ｌｉ、Ｆｅ、Ｎｉ、Ｍｇ、Ｚｎ、Ｃｏ、Ｃｒ、Ａｌ、Ｂ、Ｖ、Ｓｉ、Ｓｎ、Ｓｂ、Ｎｂ、Ｔａ、Ｍｏ、Ｔｉ及びＷからなる群から選ばれる少なくとも一種の元素を含有する請求項７に記載のリチウム二次電池。 The lithium manganate is Li, Fe, Ni, Mg, Zn, Co, Cr, Al, as the element (M 2 ) in the general formula (IV) Li a M 2 Z Mn 2 —Z O 4 ± σ . The lithium secondary battery according to claim 7 , comprising at least one element selected from the group consisting of B, V, Si, Sn, Sb, Nb, Ta, Mo, Ti, and W. 前記マンガン酸リチウムが、前記一般式（ＩＶ）ＬｉａＭ２ ＺＭｎ２−ＺＯ４±σにおける前記元素（Ｍ２）として、少なくともＬｉ、Ｎｉ及びＴｉを含有する請求項７又は８に記載のリチウム二次電池。 The lithium manganate, wherein the general formula (IV) Li a M 2 Z Mn 2-Z O 4 wherein at ± sigma element (M 2), according to claim 7 or 8 containing at least Li, Ni and Ti Lithium secondary battery. 前記マンガン酸リチウムが、粒状であり、その一次粒子の形状が八面体形で、前記一次粒子と前記一次粒子が集合した二次粒子とが混在する混合物の平均粒子径が５０μｍ以下で、比表面積が１．０ｍ２／ｇ以下である請求項７〜９のいずれかに記載のリチウム二次電池。 The lithium manganate is granular, the shape of the primary particles is octahedral, the mixture of the primary particles and the secondary particles in which the primary particles are aggregated has an average particle size of 50 μm or less, and a specific surface area the lithium secondary battery according to any one of claims 7-9 but at most 1.0 m 2 / g. 前記マンガン酸リチウムの、前記正極活物質中における含有割合が、１０〜９０質量％である請求項７〜１０のいずれかに記載のリチウム二次電池。 The lithium secondary battery according to any one of claims 7 to 10 , wherein a content ratio of the lithium manganate in the positive electrode active material is 10 to 90 mass%. 前記正極活物質に加えて負極活物質を備え、前記負極活物質が、人造黒鉛、天然黒鉛又はハードカーボンである請求項１〜１１のいずれかに記載のリチウム二次電池。 The positive active in addition to the substance comprising a negative electrode active material, the negative active material, a lithium secondary battery according to any one of claims 1 to 11 artificial graphite, natural graphite or hard carbon.
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