JP2008050259A - Lithium-manganese composite oxide and lithium secondary battery - Google Patents

Lithium-manganese composite oxide and lithium secondary battery Download PDF

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JP2008050259A
JP2008050259A JP2007247452A JP2007247452A JP2008050259A JP 2008050259 A JP2008050259 A JP 2008050259A JP 2007247452 A JP2007247452 A JP 2007247452A JP 2007247452 A JP2007247452 A JP 2007247452A JP 2008050259 A JP2008050259 A JP 2008050259A
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lithium
composite oxide
manganese composite
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Masahiro Kikuchi
政博 菊池
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Nippon Chemical Industrial Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium-manganese composite oxide useful as a cathode active material for a lithium secondary battery, which is excellent in discharge capacity and cycling characteristics and can impart high energy density, and to provide the lithium secondary battery using the above complex oxide as the cathode active material. <P>SOLUTION: The lithium-manganese composite oxide is represented by general formula (1), Li<SB>x</SB>Mn<SB>2-y</SB>Me<SB>y</SB>O<SB>4-z</SB>(wherein Me is a metal element or transition metal element of an atomic number 11 or higher except manganese; 0<x<2.0; 0≤y≤0.6; and 0≤z<2.0). The lithium content at 8a site in Rietveld analysis of X-ray diffraction is 90% or more, and the purity of the composite oxide is 90% or higher. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、リチウムマンガン複合酸化物、特にリチウム二次電池用のエネルギー密度の優れる正極活物質として有用なリチウム複合酸化物、およびそれを用いたリチウム二次電池に関するものである。   The present invention relates to a lithium-manganese composite oxide, particularly a lithium composite oxide useful as a positive electrode active material having excellent energy density for a lithium secondary battery, and a lithium secondary battery using the same.

近年、民生用電子機器のポータブル化、コードレス化が急速に進むに従い、小型電子機器の電源としてリチウム二次電池が実用化されはじめている。このリチウム二次電池については、１９８０年に水島等によりコバルト酸リチウムがリチウム二次電池の正極活物質として有用であるとの報告（非特許文献１）がなされて以来、リチウム系複合酸化物に関する研究開発が活発に進められており、これまでに正極活物質としてコバルト酸リチウム、ニッケル酸リチウム及びマンガン酸リチウムなどが知られている。   In recent years, lithium secondary batteries have begun to be put into practical use as power sources for small electronic devices as consumer electronic devices become more portable and cordless. About this lithium secondary battery, since a report (nonpatent literature 1) that lithium cobalt oxide was useful as a positive electrode active material of a lithium secondary battery by Mizushima etc. in 1980 was made, it is related with lithium type complex oxide. Research and development has been actively carried out, and lithium cobaltate, lithium nickelate, lithium manganate, and the like are known as positive electrode active materials.

マンガン酸リチウムは、コバルト酸リチウムやニッケル酸リチウムなどと比べると原料が安価であることなどから製造コストの面から、今まで様々な開発が進んでいる。   Lithium manganate has been developed in various ways from the viewpoint of production cost because raw materials are cheaper than lithium cobaltate and lithium nickelate.

それらは、例えば、Ｘ線回折で回折角２θ＝３６.５°近傍に(１１０)面のピークを有する二酸化マンガンと炭酸リチウムとを４００〜６００℃で焼成したＬｉＭｎ２Ｏ４を正極活物質とする(特許文献１)、Ｌｉ２ＭｎＯ３を活物質とする(特許文献２)、ＬｉｘＭｎ２Ｏ４(１.０２５≦ｘ≦１.１８５)を活物質とする(特許文献３)、Ｃｒ含有ＬｉＭｎ２Ｏ４を正極活物質とする(特許文献４)、ＬｉｘＭｙＭｎ２−ｙＯ４(但し、ＭはＩＩＩａ又はＩＩＩｂから選ばれた元素)の組成物を持つ複合酸化物を活物質とする(特許文献５)、針状のＬｉＭｎ２Ｏ４(特許文献６)、Ｌｉ１−ｘＭｎ２Ｏ４(０≦ｘ≦１)とＬｉ２ＭｎＯ３の複合酸化物を活物質とする(特許文献７)、硝酸リチウムと二酸化マンガンとを２５０〜４７０℃、５００〜８００℃で二段焼成して得られるＬｉＭｎ２Ｏ４(特許文献８)等が挙げられるが、他にも多くの提案がされている。 For example, LiMn 2 O 4 obtained by firing manganese dioxide and lithium carbonate having a (110) plane peak in the vicinity of a diffraction angle 2θ = 36.5 ° by X-ray diffraction at 400 to 600 ° C. is used as a positive electrode active material. (Patent Document 1), using Li 2 MnO 3 as an active material (Patent Document 2), Li x Mn 2 O 4 (1.025 ≦ x ≦ 1.185) as an active material (Patent Document 3) the Cr-containing LiMn 2 O 4 and the positive electrode active material (Patent Document 4), Li x M y Mn 2-y O 4 ( where, M is an element selected from IIIa or IIIb) composite oxide having a composition of Active material (Patent Document 5), acicular LiMn 2 O 4 (Patent Document 6), Li 1-x Mn 2 O 4 (0 ≦ x ≦ 1) and a composite oxide of Li 2 MnO 3 are activated. As a substance (Patent Document 7), lithium nitrate and manganese dioxide are mixed at 250 to 470 ° C., 50 To 800 ° C. in LiMn 2 O 4 obtained by firing two stages include (Patent Document 8), etc., but are also many proposals in other.

特開平１−１７３５７４号公報JP-A-1-173574 特開平１−２０９６６３号公報JP-A-1-209663 特開平２−２７０２６８号公報JP-A-2-270268 特開平２−６００５６号公報Japanese Patent Laid-Open No. 2-60056 特開平２−２７８６６１号公報JP-A-2-278661 特開平４−２０６３５４号公報JP-A-4-206354 特開平６−１１１８１９号公報JP-A-6-1111819 特開平７−２４５１０６号公報JP 7-245106 A マテリアル・リサーチブレイン」ｖｏｌ.１１５、７８３〜７８９頁（１９８０年）Materials Research Brain "vol.115, pp.783-789 (1980)

しかしながら、このＬｉＭｎ２Ｏ４などは、充放電を繰り返すと放電容量が著しく低下するためサイクル特性に問題があり、４.５Ｖから３.５Ｖの作動領域で使用した場合、放電容量が、数１０サイクルで初期の半分程度まで低下するといった問題が生じ、リチウムマンガン酸化物を正極活物質として使用する４Ｖ級のリチウム二次電池は、現在まで実現するのが困難な現状である。 However, this LiMn 2 O 4 or the like has a problem in cycle characteristics because the discharge capacity is remarkably lowered when charging and discharging are repeated, and when used in an operating region of 4.5 V to 3.5 V, the discharge capacity is several 10 There is a problem that the cycle is reduced to about half of the initial stage, and a 4V-class lithium secondary battery using lithium manganese oxide as a positive electrode active material is difficult to realize until now.

従って、本発明の目的は、リチウム二次電池の正極活物質とした場合、放電容量およびサイクル特性に優れる高エネルギー密度を与えることができるリチウム二次電池用正極活物質として有用なリチウムマンガン複合酸化物及び該リチウムマンガン複合酸化物を正極活物質として用いたリチウム二次電池を提供することにある。   Accordingly, an object of the present invention is to provide a lithium manganese composite oxide useful as a positive electrode active material for a lithium secondary battery that can provide a high energy density with excellent discharge capacity and cycle characteristics when used as a positive electrode active material for a lithium secondary battery. And a lithium secondary battery using the lithium manganese composite oxide as a positive electrode active material.

本発明者らは、上記の現状に着目して、鑑みたところ、リチウムマンガン複合酸化物のＸ線回折によるリートベルト解析法による８ａサイトに占めるリチウム含有率が９０％以上で、かつ上記リチウムマンガン複合酸化物の純度が９０％以上である上記リチウムマンガン複合酸化物をリチウム二次電池の正極活物質として使用した場合、放電容量およびサイクル特性などの電池特性と関係が強いことを知見し本発明を完成した。   The present inventors paid attention to the above-mentioned present situation, and as a result, the lithium content in the 8a site by the Rietveld analysis method by X-ray diffraction of the lithium manganese composite oxide is 90% or more, and the lithium manganese When the lithium manganese composite oxide having a composite oxide purity of 90% or more is used as a positive electrode active material of a lithium secondary battery, the present invention has been found to have a strong relationship with battery characteristics such as discharge capacity and cycle characteristics. Was completed.

即ち、本発明は、下記の一般式（１）
ＬｉｘＭｎ２−ｙＭｅｙＯ４−ｚ （１）
(式中、Ｍｅはマンガン以外の原子番号１１以上の金属元素又は遷移金属元素を表し、ｘは０＜ｘ＜２.０の範囲内にあり、ｙは０≦ｙ≦０.６の範囲内にあり、ｚは０≦ｚ＜２.０の範囲内にある)
で表されるリチウムマンガン複合酸化物において、Ｘ線回折によるリートベルト解析法による８ａサイトに占めるリチウム含有率が９０％以上で、かつ上記リチウムマンガン複合酸化物の純度が９０％以上であることを特徴とするリチウムマンガン複合酸化物に係る。 That is, the present invention provides the following general formula (1)
Li x Mn 2-y Me y O 4-z (1)
(In the formula, Me represents a metal element or transition metal element having an atomic number of 11 or more other than manganese, x is in the range of 0 <x <2.0, and y is in the range of 0 ≦ y ≦ 0.6. Z is in the range of 0 ≦ z <2.0)
In the lithium manganese composite oxide represented by the following formula, the lithium content in the 8a site by the Rietveld analysis method by X-ray diffraction is 90% or more, and the purity of the lithium manganese composite oxide is 90% or more. The lithium-manganese composite oxide is characterized.

更に、本発明は、前記リチウムマンガン複合酸化物を主成分として含有することを特徴とするリチウム二次電池正極活物質に係る。   Furthermore, the present invention relates to a positive electrode active material for a lithium secondary battery, comprising the lithium manganese composite oxide as a main component.

また、本発明は、前記リチウム二次電池正極活物質を用いたリチウム二次電池に係る。   The present invention also relates to a lithium secondary battery using the lithium secondary battery positive electrode active material.

本発明によれば、８ａサイトに占めるリチウム含有率が９０％以上であり、かつリチウムマンガン複合酸化物が９０％以上であるリチウムマンガン複合酸化物が得られ、例えば、リチウム二次電池の正極活物質として使用した場合、放電容量およびサイクル特性に優れる高エネルギー密度を与える二次電池用正極活物質を提供することができる。   According to the present invention, a lithium manganese composite oxide having a lithium content in the 8a site of 90% or more and a lithium manganese composite oxide of 90% or more can be obtained. When used as a substance, it is possible to provide a positive electrode active material for a secondary battery that provides a high energy density with excellent discharge capacity and cycle characteristics.

以下、本発明を詳細に説明する。
本発明に係るリチウムマンガン複合酸化物は、下記の一般式（１）
ＬｉｘＭｎ２−ｙＭｅｙＯ４−ｚ （１）
（式中、Ｍｅはマンガン以外の原子番号１１以上の金属元素又は遷移金属元素を表し、ｘは０＜ｘ＜２.０の範囲内であり、ｙは０≦ｙ≦０.６の範囲内であり、ｚは０≦ｚ＜２.０の範囲内である）
で表されるリチウムマンガン複合酸化物において、（１）Ｘ線回折によるリートベルト解析法による８ａサイトに占めるリチウム含有率が９０％以上で、かつ（２）リチウムマンガン複合酸化物の純度が９０％以上であることを構成上の特徴とする。 Hereinafter, the present invention will be described in detail.
The lithium manganese composite oxide according to the present invention has the following general formula (1):
Li x Mn 2-y Me y O 4-z (1)
(In the formula, Me represents a metal element or transition metal element having an atomic number of 11 or more other than manganese, x is in the range of 0 <x <2.0, and y is in the range of 0 ≦ y ≦ 0.6. Z is in the range of 0 ≦ z <2.0)
(1) The lithium content in the 8a site according to the Rietveld analysis method by X-ray diffraction is 90% or more, and (2) the purity of the lithium manganese composite oxide is 90%. This is the characteristic of the configuration.

なお、Ｘ線回折によるリートベルト解析法とは、文献「粉末Ｘ線回折による材料分析」（１０８〜１２２頁、１９９３年６月１日、株式会社講談社サイエンティフィク発行）などに記載されている方法であり、粉末Ｘ線回折の全パタ−ンデータの格子定数や構造パラメーター等の関数を精密化し、解析を行なうものである。リートベルト解析法の手順は後述の表１の評価方法に示す通りである。   The Rietveld analysis method by X-ray diffraction is described in the document “Material analysis by powder X-ray diffraction” (pages 108 to 122, June 1, 1993, published by Kodansha Scientific Co., Ltd.). This method refines functions such as lattice constants and structure parameters of all pattern data of powder X-ray diffraction, and performs analysis. The procedure of the Rietveld analysis method is as shown in the evaluation method of Table 1 described later.

本発明に係るリチウム複合酸化物の一つの特徴は、上記の通り、（１）Ｘ線回折によるリートベルト解析法による８ａサイトに占めるリチウム含有率が９０％以上、好ましくは９５〜１００％であり、リチウムマンガン複合酸化物中の結晶欠陥が殆どないものである。８ａサイトに占めるリチウム含有率が９０％未満では、リチウムマンガン複合酸化物の８ａサイト面にリチウム以外の他の金属イオン例えばマンガンイオンが混入してくるために、結晶構造に不規則配列を生じる傾向を示し、結晶欠陥が発生するようになるため好ましくない。   One feature of the lithium composite oxide according to the present invention is that, as described above, (1) the lithium content in the 8a site by the Rietveld analysis by X-ray diffraction is 90% or more, preferably 95 to 100%. There are almost no crystal defects in the lithium manganese composite oxide. When the lithium content in the 8a site is less than 90%, metal ions other than lithium, such as manganese ions, are mixed into the 8a site surface of the lithium manganese composite oxide, and therefore the crystal structure tends to be irregularly arranged. This is not preferable because crystal defects are generated.

また、本発明に係るリチウムマンガン複合酸化物は、（２）該リチウムマンガン複合酸化物の純度が９０％以上、好ましくは９７〜１００％であることが望ましく、純度が９０％未満では、未反応の原料が多くなるために好ましくない。   The lithium manganese composite oxide according to the present invention is preferably (2) the purity of the lithium manganese composite oxide is 90% or more, preferably 97 to 100%. This is not preferable because the amount of raw materials increases.

本発明に係るリチウムマンガン複合酸化物が、上記の様に、８ａサイトに占めるリチウム含有率が９０％未満の場合、および該リチウムマンガン複合酸化物の純度が９０％未満の場合のいずれにおいても、上記の欠陥が生じるために、リチウムマンガン複合酸化物をリチウム二次電池の正極活物質に適用すると、放電容量およびサイクル特性が低くなるために好ましない。   As described above, the lithium manganese composite oxide according to the present invention has a lithium content of less than 90% in the 8a site, and when the purity of the lithium manganese composite oxide is less than 90%, Since the above defects occur, it is not preferable to apply the lithium manganese composite oxide to the positive electrode active material of the lithium secondary battery because the discharge capacity and the cycle characteristics are lowered.

また、本発明に係るリチウムマンガン複合酸化物は、スピネル構造を有するものである。   The lithium manganese composite oxide according to the present invention has a spinel structure.

本発明に係るリチウムマンガン複合酸化物は、上記の一般式(１)で示され、上記の特性を有する。したがって、本発明のリチウムマンガン複合酸化物は、上記の特性を有するマンガン酸リチウムである場合は勿論のこと、更に、マンガン酸リチウムの結晶構造中のマンガン(Ｍｎ)の一部をマンガン以外の原子番号１１以上の金属元素又は遷移金属元素で置換した化合物、例えば、ナトリウム(Ｎａ)、マグネシウム(Ｍｇ)、アルミニウム(Ａｌ)、チタン(Ｔｉ)、バナジウム(Ｖ)、クロム(Ｃｒ)、コバルト(Ｃｏ)、鉄(Ｆｅ)、銅(Ｃｕ)、亜鉛(Ｚｎ)、イットリウム(Ｙ)、モルブデン(Ｍｏ)などより選ばれる１種以上の元素で置換した置換体であってもよく、この置換体はリチウムイオンのインターカレーション、デインターカレーション反応をより円滑に、より高い電位範囲で行なうことができる。   The lithium manganese composite oxide according to the present invention is represented by the above general formula (1) and has the above characteristics. Therefore, the lithium manganese composite oxide of the present invention is not only lithium manganate having the above characteristics, but also a part of manganese (Mn) in the crystal structure of lithium manganate is replaced with atoms other than manganese. Compounds substituted with a metal element or transition metal element of No. 11 or more, for example, sodium (Na), magnesium (Mg), aluminum (Al), titanium (Ti), vanadium (V), chromium (Cr), cobalt (Co ), Iron (Fe), copper (Cu), zinc (Zn), yttrium (Y), morbden (Mo), and the like. Lithium ion intercalation and deintercalation reactions can be carried out more smoothly and in a higher potential range.

次に、本発明のリチウムマンガン複合酸化物の製造方法について説明する。
本発明に係るリチウムマンガン複合酸化物の製造方法は、マンガン原料もしくはマンガン原料とマンガンを除く原子番号１１以上の金属元素又は遷移金属元素原料（以下「金属又は遷移金属」という。）の原子比が各々２−ｙおよびｙ(式中、ｙは０≦ｙ≦０.６の範囲内にある)にあるマンガンもしくはマンガンとマンガンを除く原子番号１１以上の金属元素又は遷移金属元素の酸化物、水酸化物、炭酸塩、硝酸塩及び有機酸塩からなる群から選択された１種または２種以上より構成される出発原料に対して原子比でｘ(式中、ｘは０＜ｘ＜２.０の範囲内にある)のリチウム原料を少なくとも２回以上に分けて添加して焼成することを特徴とする前記一般式（１）で表されるリチウムマンガン複合酸化物を製造する方法である。 Next, the manufacturing method of the lithium manganese composite oxide of this invention is demonstrated.
In the method for producing a lithium manganese composite oxide according to the present invention, the atomic ratio of a manganese element or a metal element having a atomic number of 11 or more excluding manganese and manganese (hereinafter referred to as “metal or transition metal”) is excluded. Each of 2-y and y (wherein y is in the range of 0 ≦ y ≦ 0.6), oxides of metal elements or transition metal elements having an atomic number of 11 or more excluding manganese and manganese, water X in terms of atomic ratio with respect to a starting material composed of one or more selected from the group consisting of oxides, carbonates, nitrates and organic acid salts (wherein x is 0 <x <2.0) The lithium-manganese composite oxide represented by the general formula (1) is produced by adding and firing the lithium raw material (within the range of 2) at least twice.

出発原料として使用されるリチウム原料、マンガン原料並びに金属又は遷移金属原料は、工業的に入手できるものであれば何れのものでもよいが、例えばそれぞれの金属の酸化物、水酸化物、炭酸塩、硝酸塩および有機酸塩などが挙げられる。   The lithium raw material, manganese raw material and metal or transition metal raw material used as starting materials may be any industrially available materials, such as oxides, hydroxides, carbonates of the respective metals, Examples thereof include nitrates and organic acid salts.

また、本発明で使用する出発原料は、いずれにおいても製造履歴は問わないが、可及的に不純物含有量が少ないものを選定することが好ましい。   In addition, the starting material used in the present invention is not limited to any production history, but it is preferable to select a starting material having as little impurity content as possible.

リチウム原料の添加割合は、反応系に使用するリチウム原料の全量を、例えば２回で分けて添加する場合は、初めに全量の２／３を添加して焼成し、２回目に１／３を添加して焼成する。また、初めに１／２、１／２と均等に添加する方法などである。また、３回に分けて行う場合は、全量の４／７、２／７、１／７に分けて添加する方法か、または１／３、１／３、１／３と均等に分ける方法などである。   When adding the total amount of the lithium raw material used in the reaction system, for example, in two portions, for example, 2/3 of the total amount is first added and fired, and 1/3 is added the second time. Add and bake. In addition, there is a method of adding ½ and ½ equally at the beginning. In addition, when it is divided into three times, it is a method of adding in 4/7, 2/7, 1/7 of the total amount, or a method of dividing equally into 1/3, 1/3, 1/3, etc. It is.

本発明のリチウムマンガン複合酸化物の製造方法の一例を示すと、所定量のマンガン原料またはマンガン原料と金属又は遷移金属原料量に対して必要量のリチウム原料の４／７重量部を乾式で混合し、４００〜５００℃で、５〜２４時間焼成する。この時、混合を湿式で行う場合には、リチウム原料水溶液にマンガン原料またはマンガン原料と金属又は遷移金属原料を混合し、撹拌し、水分を除去して乾燥することができる。   An example of the method for producing a lithium manganese composite oxide of the present invention is as follows. A predetermined amount of manganese raw material or manganese raw material is mixed with 4/7 parts by weight of a required amount of lithium raw material with respect to the amount of metal or transition metal raw material. And calcining at 400 to 500 ° C. for 5 to 24 hours. At this time, when the mixing is performed in a wet manner, a manganese raw material or a manganese raw material and a metal or a transition metal raw material are mixed in a lithium raw material aqueous solution, and the mixture is stirred to remove moisture and dried.

焼成後、冷却し、再度混合し、必要に応じて粉砕し、再度焼成する。この時、焼成温度は、前回の焼成温度より高温で行うのが良く、例えば５００〜１１００℃、５〜２４時間焼成する。この操作パターンを１回として、２回焼成であれば、リウチム原料の残部を添加して上記焼成操作を繰り返し、３回焼成であれば、リウチム原料の添加及び焼成操作をあと２回繰り返す。   After firing, it is cooled, mixed again, ground if necessary, and fired again. At this time, the firing temperature is preferably higher than the previous firing temperature. For example, firing is performed at 500 to 1100 ° C. for 5 to 24 hours. With this operation pattern as one time, if the firing is performed twice, the above-described firing operation is repeated by adding the remaining portion of the raw material, and if the firing is performed three times, the addition of the raw material and the firing operation are repeated two more times.

また、他の焼成方法としては、始めに、所定量のマンガン原料またはマンガン原料と金属又は遷移金属原料量に対して必要量のリチウム原料の４／７重量部を乾式で混合し、４００〜５００℃で、５〜２４時間焼成する。この時、前記と同ように混合は乾式又は湿式の何れでも良い。焼成後、冷却し、リチウム原料の２／７重量部を添加して再度混合し、必要に応じて粉砕混合する。次いで、５００〜１１００℃で、５〜２４時間同様に焼成する。この時、焼成温度は、１回目の焼成温度より高温で行うことが好ましい。焼成終了後、通常の方法で冷却し、リチウム原料の残余即ち１／７重量部を添加し、再度混合し、必要に応じて粉砕混合する。次いで、再度４００〜５００℃、５〜２４時間程度焼成する。焼成後、冷却し、混合し、必要に応じて粉砕混合することにより、リチウムマンガン複合酸化物を得ることができる。   In addition, as another firing method, first, a predetermined amount of manganese raw material or manganese raw material and 4/7 parts by weight of a required amount of lithium raw material with respect to the amount of metal or transition metal raw material are mixed in a dry process, and 400 to 500 Bake at 5 ° C. for 5-24 hours. At this time, the mixing may be either dry or wet as described above. After firing, the mixture is cooled, 2/7 parts by weight of the lithium raw material is added and mixed again, and pulverized and mixed as necessary. Then, it is similarly fired at 500 to 1100 ° C. for 5 to 24 hours. At this time, the firing temperature is preferably higher than the first firing temperature. After the completion of firing, the mixture is cooled by a normal method, the remainder of the lithium raw material, that is, 1/7 parts by weight, is added, mixed again, and pulverized and mixed as necessary. Next, it is fired again at 400 to 500 ° C. for about 5 to 24 hours. After firing, the mixture is cooled, mixed, and pulverized and mixed as necessary to obtain a lithium manganese composite oxide.

この方法において、２回焼成の場合は、上記方法で初めの１回と２回の焼成条件で行えば良いものである。   In this method, in the case of two-time firing, the above method may be performed under the first and second firing conditions.

上記製造方法での焼成雰囲気は、大気中又は酸素雰囲気中であるが、好ましくは酸素雰囲気中である。   The firing atmosphere in the above production method is in the air or in an oxygen atmosphere, but is preferably in an oxygen atmosphere.

なお、上述のようにリチウムマンガン複合酸化物を製造する際に、リチウム原料を分割して添加することにより、リチウム原料を全量一度に添加して焼成する場合よりも得られるリチウムマンガン複合酸化物のサイクル特性が良くなる。   In addition, when the lithium manganese composite oxide is produced as described above, by adding the lithium raw material in a divided manner, the lithium manganese composite oxide can be obtained more than when the entire amount of the lithium raw material is added and fired at once. Cycle characteristics are improved.

リチウム原料、マンガン原料およびマンガン以外の金属又は遷移金属原料の配合比は、リチウム(Ｌｉ)、マンガン(Ｍｎ)およびマンガン以外の金属又は遷移金属(Ｍｅ)の原子比が各々ｘ(Ｌｉ)、２−ｙ(Ｍｎ)、ｙ(Ｍｅ)(但し、ｘは０＜ｘ＜２.０の範囲内にあり、ｙは０≦ｙ≦０.６の範囲内にある）を満足するように選択される。例えば、配合比は(Ｍｎ又はＭｎ＋Ｍｅ)／Ｌｉ比として２付近に設定する場合、原料の性状や焼成条件などにより前記配合比は２前後で多少の幅をもたせることは許容される。   The compounding ratio of lithium raw material, manganese raw material and metal other than manganese or transition metal raw material is such that the atomic ratio of lithium (Li), manganese (Mn) and metal other than manganese or transition metal (Me) is x (Li), 2 -Y (Mn), y (Me) (where x is in the range 0 <x <2.0 and y is in the range 0≤y≤0.6). The For example, when the blending ratio is set near 2 as the (Mn or Mn + Me) / Li ratio, the blending ratio is allowed to have a width of around 2 depending on the properties of the raw materials and firing conditions.

上記反応の冷却は、通常は炉内で徐々に冷却するが、好ましくは空気中で放冷するのがよく、さらには冷水中で急冷してもよい。   The reaction is usually gradually cooled in a furnace, but preferably cooled in air, and may be further quenched in cold water.

また、上記のマンガン原料およびリチウム原料、若しくはマンガン原料、金属又は遷移金属原料およびリチウム原料を均一に混合して加圧成形して成形体を作製し、この成形体を上記と同様の方法で焼成し、焼成後、冷却する方法でもよい。   Further, the above manganese raw material and lithium raw material, or manganese raw material, metal or transition metal raw material and lithium raw material are uniformly mixed and pressure-molded to produce a molded body, and this molded body is fired in the same manner as above. Alternatively, a method of cooling after firing may be used.

上記の方法により製造される本発明のリチウムマンガン複合酸化物は、Ｘ線回折によるリートベルト解析法による８ａサイトに占めるリチウム含有率が９０％以上で結晶中の欠陥が極めて少なく、且つリチウムマンガン複合酸化物の純度が９０％以上と不純物の少ないものである。かかる化合物は、スピネル型を有する。   The lithium manganese composite oxide of the present invention produced by the above method has a lithium content of 90% or more in the 8a site according to the Rietveld analysis method by X-ray diffraction, and has very few defects in the crystal. The purity of the oxide is 90% or more and there are few impurities. Such compounds have a spinel type.

また、上記の方法により得られた本発明のリチウムマンガン複合酸化物は、リチウム二次電池正極活物質として有用である。   Moreover, the lithium manganese composite oxide of the present invention obtained by the above method is useful as a positive electrode active material for a lithium secondary battery.

更に、本発明のリチウムマンガン複合酸化物を主成分として含有するリチウム二次電池正極活物質で導電性基板を被覆してリチウム二次電池用正極板を得ることができ、また、その正極板を用いることによりリチウム二次電池を提供することができる。   Furthermore, a positive electrode plate for a lithium secondary battery can be obtained by coating a conductive substrate with a lithium secondary battery positive electrode active material containing the lithium manganese composite oxide of the present invention as a main component. By using it, a lithium secondary battery can be provided.

次に、本発明に係るリチウム二次電池の基本的な構成の一例を示す。
上記のようにして製造した本発明のリチウムマンガン複合化合物粉末を主成分として、黒鉛粉末、ポリフッ化ビニリデンなどを混合加工して正極剤（リチウム二次電池正極活物質）とし、これを有機溶媒に分散させて混練ペーストを調製する。該混練ペーストをアルミ箔などの導電性基板に塗布した後、乾燥し、加圧して適宜の形状に切断して正極板を得る。 Next, an example of a basic configuration of the lithium secondary battery according to the present invention is shown.
The lithium manganese composite compound powder of the present invention produced as described above is used as a main component, and graphite powder, polyvinylidene fluoride, etc. are mixed and processed into a positive electrode agent (lithium secondary battery positive electrode active material), which is used as an organic solvent. Disperse to prepare a kneaded paste. The kneaded paste is applied to a conductive substrate such as an aluminum foil, dried, pressed and cut into an appropriate shape to obtain a positive electrode plate.

従来、リチウム二次電池用正極活物質に用いられるマンガン酸リチウムの合成は難しく、その結果、得られるマンガン酸リチウムは８ａサイトのリチウム含有率が小さく、リチウムの欠損が大きいことにより電池性能に悪影響を及ぼしていた。   Conventionally, it is difficult to synthesize lithium manganate used as a positive electrode active material for a lithium secondary battery. As a result, the obtained lithium manganate has a small lithium content at the 8a site and a large lithium deficiency, which adversely affects battery performance. Was exerting.

本発明のリチウムマンガン複合酸化物は、結晶中の欠陥が少ない極めて化学量論的な化合物である。かかる化合物中の結晶中の欠陥は、Ｘ線回折によリートベルト解析法により確認できるが、それは結晶構造中の８ａサイトに占めるリチウム含有率が９０％以上、上記リチウムマンガン複合酸化物の純度が９０％以上であり、例えばリチウム二次電池の正極活物質として使用する場合、放電容量に優れ、およびサイクル特性に優れた高エネルギー密度を有するものである。   The lithium manganese composite oxide of the present invention is a very stoichiometric compound with few defects in the crystal. The defects in the crystals in such compounds can be confirmed by Rietveld analysis by X-ray diffraction, which means that the lithium content in the 8a site in the crystal structure is 90% or more and the purity of the lithium manganese composite oxide is high. For example, when used as a positive electrode active material of a lithium secondary battery, it has a high energy density with excellent discharge capacity and excellent cycle characteristics.

以下に、本発明にかかる実施例を詳細に説明する。
製造例１
電解合成二酸化マンガン８.６９ｇと炭酸リチウム１.０６ｇを粉砕混合し、アルミナるつぼに入れ、４５０℃まで１００℃／時間で昇温し、その後８時間空気雰囲気下で焼成し、１００℃／時間で室温まで冷却した。次に、得られたリチウムマンガン酸化物を粉砕した後、７２５℃で８時間焼成した。この時の昇温速度及び冷却速度は１００℃／時間であった。
この様にして得られたリチウムマンガン酸化物に更に炭酸リチウム０.５３ｇを加えて粉砕混合し、前記と同様に４５０℃で８時間焼成し、冷却粉砕後再び７２５℃で８時間焼成を行った。
更に、得られたリチウムマンガン酸化物に炭酸リチウム０.２６ｇを加えて粉砕混合し、先程と同様に４５０℃で８時間焼成し、冷却粉砕後再び７２５℃で８時間焼成を行った。
この様にして得られたリチウムマンガン複合酸化物はＬｉＭｎ２Ｏ４の組成を有するものであった。このリチウムマンガン複合酸化物の８ａサイトのリチウム含有率及び純度、初期容量、サイクル特性を表１に示す。また、得られたリチウムマンガン複合酸化物のＸ線回折の結果を図１に示す。 Embodiments according to the present invention will be described in detail below.
Production Example 1
8.69 g of electrolytically synthesized manganese dioxide and 1.06 g of lithium carbonate are pulverized and mixed, put in an alumina crucible, heated to 450 ° C. at 100 ° C./hour, then fired in an air atmosphere for 8 hours, at 100 ° C./hour. Cooled to room temperature. Next, after the obtained lithium manganese oxide was pulverized, it was baked at 725 ° C. for 8 hours. The heating rate and cooling rate at this time were 100 ° C./hour.
To the lithium manganese oxide thus obtained, 0.53 g of lithium carbonate was further added and pulverized and mixed, and baked at 450 ° C. for 8 hours in the same manner as described above, and then baked again at 725 ° C. for 8 hours after cooling and pulverization. .
Further, 0.26 g of lithium carbonate was added to the obtained lithium manganese oxide and pulverized and mixed. The mixture was baked at 450 ° C. for 8 hours in the same manner as described above, and baked again at 725 ° C. for 8 hours after cooling and pulverization.
The lithium manganese composite oxide thus obtained had a composition of LiMn 2 O 4 . Table 1 shows the lithium content and purity, initial capacity, and cycle characteristics of the 8a site of this lithium manganese composite oxide. Moreover, the result of the X-ray diffraction of the obtained lithium manganese composite oxide is shown in FIG.

製造例２
電解合成二酸化マンガン８.６９ｇと炭酸リチウム１.８５ｇを粉砕混合し、アルミナるつぼに入れ、４５０℃まで１００℃／時間で昇温させ、その後１２時間空気雰囲気下で焼成し、１００℃／時間で室温まで冷却した。得られたリチウムマンガン酸化物を粉砕した後、再び７２５℃で１２時間焼成した。この時の昇温速度及び冷却速度は１００℃／時間であった。
この様にして得られたリチウムマンガン酸化物に炭酸リチウム０.６２ｇを加えて粉砕混合し、先程と同様に４５０℃で１２時間焼成し、冷却粉砕後再び７２５℃で１２時間焼成を行った。得られたリチウムマンガン複合酸化物はＬｉＭｎ２Ｏ４の組成を有するものであった。この化合物の８ａサイトのリチウム含有率及び純度、初期容量、サイクル特性を表１に示す。 Production Example 2
8.69 g of electrolytically synthesized manganese dioxide and 1.85 g of lithium carbonate were pulverized and mixed, put in an alumina crucible, heated to 450 ° C. at 100 ° C./hour, then baked in an air atmosphere for 12 hours, at 100 ° C./hour. Cooled to room temperature. The obtained lithium manganese oxide was pulverized and then fired again at 725 ° C. for 12 hours. The heating rate and cooling rate at this time were 100 ° C./hour.
Lithium manganese oxide thus obtained was mixed with 0.62 g of lithium carbonate, pulverized and mixed, baked at 450 ° C. for 12 hours in the same manner as described above, and baked again at 725 ° C. for 12 hours after cooling and pulverization. The obtained lithium manganese composite oxide had a composition of LiMn 2 O 4 . Table 1 shows the lithium content and purity, initial capacity, and cycle characteristics of the 8a site of this compound.

製造例３
炭酸マンガン１１.５０ｇと水酸化リチウム一水和物１.２０ｇを粉砕混合し、アルミナるつぼに入れ、４５０℃まで１００℃／時間で昇温し、その後８時間空気雰囲気下で焼成し、１００℃／時間で室温まで冷却した。得られたリチウムマンガン酸化物を粉砕した後、再び７２５℃で８時間焼成した。この時の昇温速度及び冷却速度は１００℃／時間であった。
この様にして得られたリチウムマンガン酸化物に水酸化リチウム一水和物０.６０gを加えて粉砕混合し、先程と同様に４５０℃で８時間焼成し，冷却粉砕後再び７２５℃で８時間焼成を行った。
更に、得られたリチウムマンガン酸化物に水酸化リチウム一水和物０.３０ｇを加えて粉砕混合し、先程と同様に４５０℃で８時間焼成し，冷却粉砕後再び７２５℃で８時間焼成を行った。得られたリチウムマンガン複合酸化物はＬｉＭｎ２Ｏ４の組成を有するものであった。この化合物の８ａサイトのリチウム含有率及び純度、初期容量、サイクル特性を表１に示す。 Production Example 3
11.50 g of manganese carbonate and 1.20 g of lithium hydroxide monohydrate were pulverized and mixed, put in an alumina crucible, heated to 450 ° C. at 100 ° C./hour, and then fired in an air atmosphere for 8 hours. / Hour at room temperature. The obtained lithium manganese oxide was pulverized and then fired again at 725 ° C. for 8 hours. The heating rate and cooling rate at this time were 100 ° C./hour.
To the lithium manganese oxide thus obtained, 0.60 g of lithium hydroxide monohydrate was added and ground and mixed, fired at 450 ° C. for 8 hours as before, cooled and ground again, and again at 725 ° C. for 8 hours. Firing was performed.
Further, 0.30 g of lithium hydroxide monohydrate was added to the obtained lithium manganese oxide and pulverized and mixed. The mixture was baked at 450 ° C. for 8 hours in the same manner as described above, and then baked again at 725 ° C. for 8 hours. went. The obtained lithium manganese composite oxide had a composition of LiMn 2 O 4 . Table 1 shows the lithium content and purity, initial capacity, and cycle characteristics of the 8a site of this compound.

製造例４
電解合成二酸化マンガン８.２６ｇと水酸化アルミニウム３.９０ｇと炭酸リチウム１.０６ｇを粉砕混合し、アルミナるつぼに入れ、４５０℃まで１００℃／時間で昇温し、その後８時間空気雰囲気下で焼成し、１００℃／時間で室温まで冷却した。得られたリチウムマンガン複合酸化物を粉砕した後、再び７２５℃で８時間焼成した。この時の昇温速度及び冷却速度は１００℃／時間であった。
この様にして得られたリチウムマンガン複合酸化物に炭酸リチウム０.５３ｇを加えて粉砕混合し、先程と同様に４５０℃で８時間焼成し、冷却粉砕後再び７２５℃で８時間焼成を行った。
更に、得られたリチウムマンガン複合酸化物に炭酸リチウム０.２６ｇを加えて粉砕混合し、先程と同様に４５０℃で８時間焼成し、冷却粉砕後再び７２５℃で８時間焼成を行った。得られたリチウムマンガン複合酸化物はＬｉＭｎ１．９Ａｌ０．１Ｏ４の組成を有するものであった。この化合物の８ａサイトのリチウム含有率及び純度、初期容量、サイクル特性を表１に示す。また、得られたリチウムマンガン複合酸化物のＸ線回折の結果を図２に示す。 Production Example 4
8.26 g of electrolytically synthesized manganese dioxide, 3.90 g of aluminum hydroxide and 1.06 g of lithium carbonate are ground and mixed, put in an alumina crucible, heated to 450 ° C. at 100 ° C./hour, and then fired in an air atmosphere for 8 hours. And cooled to room temperature at 100 ° C./hour. The obtained lithium manganese composite oxide was pulverized and then fired again at 725 ° C. for 8 hours. The heating rate and cooling rate at this time were 100 ° C./hour.
0.53 g of lithium carbonate was added to the lithium manganese composite oxide thus obtained and pulverized and mixed. The mixture was baked at 450 ° C. for 8 hours in the same manner as described above, and baked again at 725 ° C. for 8 hours after cooling and pulverization. .
Further, 0.26 g of lithium carbonate was added to the obtained lithium manganese composite oxide and pulverized and mixed. The mixture was baked at 450 ° C. for 8 hours in the same manner as described above, and baked again at 725 ° C. for 8 hours after cooling and pulverization. The obtained lithium manganese composite oxide had a composition of LiMn 1.9 Al 0.1 O 4 . Table 1 shows the lithium content and purity, initial capacity, and cycle characteristics of the 8a site of this compound. Moreover, the result of the X-ray diffraction of the obtained lithium manganese composite oxide is shown in FIG.

製造例５
電解合成二酸化マンガン８.２６ｇと水酸化コバルト４.６５ｇと炭酸リチウム１.０６ｇを粉砕混合し、アルミナるつぼに入れ、４５０℃まで１００℃／時間で昇温し、その後８時間空気雰囲気下で焼成し、１００℃／時間で室温まで冷却した。得られたリチウムマンガン複合酸化物を粉砕した後，再び７２５℃で８時間焼成した。この時の昇温速度及び冷却速度は１００℃／時間であった。
この様にして得られたリチウムマンガン複合酸化物に炭酸リチウム０.５３ｇを加えて粉砕混合し、先程と同様に４５０℃で８時間焼成し、冷却粉砕後再び７２５℃で８時間焼成を行った。
更に、得られたリチウムマンガン複合酸化物に炭酸リチウム０.２６gを加えて粉砕混合し、先程と同様に４５０℃で８時間焼成し、冷却粉砕後再び７２５℃で８時間焼成を行った。得られたリチウムマンガン複合酸化物はＬｉＭｎ１．９Ｃｏ０．１Ｏ４の組成を有するものであった。この化合物の８ａサイトのリチウム含有率及び純度、初期容量、サイクル特性を表１に示す。また、得られたリチウムマンガン複合酸化物のＸ線回折の結果を図３に示す。 Production Example 5
8.26 g of electrolytically synthesized manganese dioxide, 4.65 g of cobalt hydroxide and 1.06 g of lithium carbonate are ground and mixed, put in an alumina crucible, heated to 450 ° C. at 100 ° C./hour, and then fired in an air atmosphere for 8 hours. And cooled to room temperature at 100 ° C./hour. The obtained lithium manganese composite oxide was pulverized and then fired again at 725 ° C. for 8 hours. The heating rate and cooling rate at this time were 100 ° C./hour.
0.53 g of lithium carbonate was added to the lithium manganese composite oxide thus obtained and pulverized and mixed. The mixture was baked at 450 ° C. for 8 hours in the same manner as described above, and baked again at 725 ° C. for 8 hours after cooling and pulverization. .
Further, 0.26 g of lithium carbonate was added to the obtained lithium manganese composite oxide and pulverized and mixed. The mixture was baked at 450 ° C. for 8 hours in the same manner as described above, and baked again at 725 ° C. for 8 hours after cooling and pulverization. The obtained lithium manganese composite oxide had a composition of LiMn 1.9 Co 0.1 O 4 . Table 1 shows the lithium content and purity, initial capacity, and cycle characteristics of the 8a site of this compound. Moreover, the result of the X-ray diffraction of the obtained lithium manganese composite oxide is shown in FIG.

製造例６
電解合成二酸化マンガン８.２６ｇと水酸化ニッケル４.６４ｇと炭酸リチウム１.０６ｇを粉砕混合し、アルミナるつぼに入れ、４５０℃まで１００℃／時間で昇温し、その後８時間空気雰囲気下で焼成し、１００℃／時間で室温まで冷却した。得られたリチウムマンガン複合酸化物を粉砕した後、再び７２５℃で８時間焼成した。この時の昇温速度及び冷却速度は１００℃／時間であった。
この様にして得られたリチウムマンガン複合酸化物に炭酸リチウム０.５３ｇを加えて粉砕混合し、先程と同様に４５０℃で８時間焼成し、冷却粉砕後再び７２５℃で８時間焼成を行った。
更に、得られたリチウムマンガン複合酸化物に炭酸リチウム０.２６ｇを加えて粉砕混合し、先程と同様に４５０℃で８時間焼成し、冷却粉砕後再び７２５℃で８時間焼成を行った。得られたリチウムマンガン複合酸化物はＬｉＭｎ１．９Ｎｉ０．４Ｏ４の組成を有するものであった。この化合物の８ａサイトのリチウム含有率及び純度、初期容量、サイクル特性を表１に示す。 Production Example 6
8.26 g of electrolytically synthesized manganese dioxide, 4.64 g of nickel hydroxide, and 1.06 g of lithium carbonate are ground and mixed, put in an alumina crucible, heated to 450 ° C. at 100 ° C./hour, and then fired in an air atmosphere for 8 hours. And cooled to room temperature at 100 ° C./hour. The obtained lithium manganese composite oxide was pulverized and then fired again at 725 ° C. for 8 hours. The heating rate and cooling rate at this time were 100 ° C./hour.
0.53 g of lithium carbonate was added to the lithium manganese composite oxide thus obtained and pulverized and mixed. The mixture was baked at 450 ° C. for 8 hours in the same manner as described above, and baked again at 725 ° C. for 8 hours after cooling and pulverization. .
Further, 0.26 g of lithium carbonate was added to the obtained lithium manganese composite oxide and pulverized and mixed. The mixture was baked at 450 ° C. for 8 hours in the same manner as described above, and baked again at 725 ° C. for 8 hours after cooling and pulverization. The obtained lithium manganese composite oxide had a composition of LiMn 1.9 Ni 0.4 O 4 . Table 1 shows the lithium content and purity, initial capacity, and cycle characteristics of the 8a site of this compound.

製造例７
電解合成二酸化マンガン８.６９ｇと炭酸リチウム０.６２ｇを粉砕混合し、アルミナるつぼに入れ、４５０℃まで１００℃／時間で昇温し、その後８時間空気雰囲気下で焼成し、１００℃／時間で室温まで冷却した。得られたリチウムマンガン酸化物を粉砕した後、再び７２５℃で８時間焼成する。この時の昇温速度及び冷却速度は１００℃／時間であった。
この様にして得られたリチウムマンガン酸化物に炭酸リチウム０.６２ｇを加えて粉砕混合し、先程と同様に４５０℃で８時間焼成し、冷却粉砕後再び７２５℃で８時間焼成を行った。
更に、得られたリチウムマンガン酸化物に炭酸リチウム０.６２ｇを加えて粉砕混合し、先程と同様に４５０℃で８時間焼成し、冷却粉砕後再び７２５℃で８時間焼成を行った。得られたリチウムマンガン複合酸化物はＬｉＭｎ２Ｏ４の組成を有するものであった。この化合物の８ａサイトのリチウム含有率及び純度、初期容量、サイクル特性を表１に示す。 Production Example 7
8.69 g of electrolytically synthesized manganese dioxide and 0.62 g of lithium carbonate were pulverized and mixed, put in an alumina crucible, heated to 450 ° C. at 100 ° C./hour, then fired in an air atmosphere for 8 hours, at 100 ° C./hour. Cooled to room temperature. The obtained lithium manganese oxide is pulverized and then fired again at 725 ° C. for 8 hours. The heating rate and cooling rate at this time were 100 ° C./hour.
0.62 g of lithium carbonate was added to the lithium manganese oxide thus obtained, and pulverized and mixed. The mixture was baked at 450 ° C. for 8 hours in the same manner as described above, and baked again at 725 ° C. for 8 hours after cooling and pulverization.
Further, 0.62 g of lithium carbonate was added to the obtained lithium manganese oxide and pulverized and mixed. The mixture was baked at 450 ° C. for 8 hours in the same manner as described above, and baked again at 725 ° C. for 8 hours after cooling and pulverization. The obtained lithium manganese composite oxide had a composition of LiMn 2 O 4 . Table 1 shows the lithium content and purity, initial capacity, and cycle characteristics of the 8a site of this compound.

製造例８
実施例１の空気雰囲気下での焼成を、酸素雰囲気下で行った他は、実施例１と同様の操作にてリチウムマンガン複合酸化物を得た。この化合物の８ａサイトのリチウム含有率及び純度、初期容量、サイクル特性を表１に示す。 Production Example 8
A lithium manganese composite oxide was obtained in the same manner as in Example 1 except that firing in the air atmosphere of Example 1 was performed in an oxygen atmosphere. Table 1 shows the lithium content and purity, initial capacity, and cycle characteristics of the 8a site of this compound.

（１）リチウム二次電池の作製：
上記のように製造したリチウムマンガン複合酸化物７０重量％、黒鉛粉末２０重量％、ポリフッ化ビニリデン１０重量％を混合して正極剤とし、これを２−メチルピロリドンに分散させて混練ペーストを調製した。該混練ペーストをアルミ箔に塗布したのち乾燥し、２トン／ｃｍ２の圧力によりプレスして２ｃｍ角に打ち抜いて正極板を得た。
この正極板を用いて、セパレーター、負極、集電板、取り付け金具、外部端子、電解液等の各部材を使用してリチウム二次電池を製作した。このうち、負極は結晶化度の高いカーボンを用い、電解液にはジエチルカーボネートとエチレンカーボネートの１：１混合液１リットルにＬｉＣｌＯ４１モルを溶解したものを使用した。 (1) Production of lithium secondary battery:
70% by weight of the lithium manganese composite oxide produced as described above, 20% by weight of graphite powder, and 10% by weight of polyvinylidene fluoride were mixed to prepare a positive electrode agent, which was dispersed in 2-methylpyrrolidone to prepare a kneaded paste. . The kneaded paste was applied to an aluminum foil, dried, pressed with a pressure of 2 ton / cm 2 , and punched into a 2 cm square to obtain a positive electrode plate.
Using this positive electrode plate, a lithium secondary battery was manufactured using each member such as a separator, a negative electrode, a current collector plate, a mounting bracket, an external terminal, and an electrolytic solution. Among these, carbon having a high crystallinity was used for the negative electrode, and 1 mol of LiClO 4 was dissolved in 1 liter of a 1: 1 mixture of diethyl carbonate and ethylene carbonate as the electrolyte.

（２）リチウム二次電池の性能評価：
作製したリチウム二次電池を作動させ、初期放電容量および容量保持率を測定して電池性能を評価した。その結果を、焼成条件、Ｘ線回折によるリートベルト解析法による８ａサイトに占めるリチウム含有率、およびリチウムマンガン複合酸化物の純度と対比させて表１に示した。 (2) Performance evaluation of lithium secondary battery:
The produced lithium secondary battery was operated, and the initial discharge capacity and capacity retention were measured to evaluate the battery performance. The results are shown in Table 1 in comparison with the firing conditions, the lithium content in the 8a site by the Rietveld analysis method by X-ray diffraction, and the purity of the lithium manganese composite oxide.

（３）評価方法
Ａ．リートベルト解析法の手順は次の通りである。
始めに化合物中のＬｉ含有量をＩＣＰ分析法により、また、該化合物中のＭｎ含有量を下記のＢにより測定した。次いで、Ｍｎの価数を求めた後、下記のリートベルト解析法を行った。
(１)粉末Ｘ線回折パタ−ンのピークを指数づけし、空間群を絞り込む；
(２)最小２乗法あるいはＰａｗｌｅｙ法により格子定数を精密化する；
(３)結晶学的な知見及び化学組成等から大まかな原子配置を推定する；
(４)(３)で構築した構造モデルに基づいて、粉末Ｘ線回折図形をシュミレートする；
(５)リートベルト解析を行ない、８ａサイトに占めるリチウム含有量を測定する。 (3) Evaluation method The procedure of the Rietveld analysis method is as follows.
First, the Li content in the compound was measured by ICP analysis, and the Mn content in the compound was measured by the following B. Next, after obtaining the valence of Mn, the following Rietveld analysis method was performed.
(1) Index the powder X-ray diffraction pattern peaks to narrow down the space group;
(2) Refine the lattice constant by least squares method or Pawley method;
(3) Estimating the approximate atomic arrangement from crystallographic knowledge and chemical composition;
(4) Simulate a powder X-ray diffraction pattern based on the structural model constructed in (3);
(5) Rietveld analysis is performed and the lithium content in the 8a site is measured.

Ｂ．リチウムマンガン複合酸化物の純度測定
得られた試料を塩酸等の鉱酸に溶解させ、ロッセル塩を加えて、ＮＨ３−ＮＨ４Ｃｌ緩衝液でｐＨを８に調整する。さらにアスコルビン酸を加え、エリオクローム・ブラックＴ(ＢＴ)指示薬で、ＥＤＴＡにより滴定を行い全マンガン量を測定した。この値より、 ＬｉＭｎ２Ｏ４の純度を換算した。(ＢＴ指示薬による直接滴定「キレート滴定法、３４２〜３４４頁、上野著、南江堂出版、昭和３１年６月１５日初版) B. Determination of purity of lithium manganese composite oxide The obtained sample is dissolved in mineral acid such as hydrochloric acid, Rossell salt is added, and the pH is adjusted to 8 with NH 3 —NH 4 Cl buffer. Further, ascorbic acid was added, and titration was performed by EDTA with an Eriochrome Black T (BT) indicator to measure the total manganese amount. From this value, the purity of LiMn 2 O 4 was converted. (Direct titration with BT indicator "Chelate titration method, pages 342-344, Ueno, Minamiedo Publishing, first edition on June 15, 1951)

Ｃ．放電容量
放電容量は正極に対して１ｍＡ／ｃｍ２で４.３Ｖまで充電した後、３.０Ｖまで放電させる充放電を繰り返すことにより測定し、サイクル特性は前記の充放電を反復した結果から、下記の式により算出した。
サイクル特性(％)＝(１０サイクル目の放電容量／１サイクル目の放電容量)
×１００ C. Discharge capacity The discharge capacity was measured by repeatedly charging and discharging to 3.0 V after charging to 4.3 V at 1 mA / cm 2 with respect to the positive electrode. It was calculated by the following formula.
Cycle characteristics (%) = (discharge capacity at 10th cycle / discharge capacity at 1st cycle)
× 100

Figure 2008050259
Figure 2008050259

製造例１で得られたリチウムマンガン複合酸化物のＸ線回折の結果を示す図である。FIG. 4 is a diagram showing the results of X-ray diffraction of the lithium manganese composite oxide obtained in Production Example 1. 製造例４で得られたリチウムマンガン複合酸化物のＸ線回折の結果を示す図である。It is a figure which shows the result of the X-ray diffraction of the lithium manganese complex oxide obtained by manufacture example 4. 製造例５で得られたリチウムマンガン複合酸化物のＸ線回折の結果を示す図である。6 is a diagram showing the results of X-ray diffraction of the lithium manganese composite oxide obtained in Production Example 5. FIG.

Claims (4)

下記の一般式（１）
ＬｉｘＭｎ２−ｙＭｅｙＯ４−ｚ （１）
(式中、Ｍｅはマンガン以外の原子番号１１以上の金属元素又は遷移金属元素を表し、ｘは０＜ｘ＜２.０の範囲内にあり、ｙは０≦ｙ≦０.６の範囲内にあり、ｚは０≦ｚ＜２.０の範囲内にある)
で表されるリチウムマンガン複合酸化物において、Ｘ線回折によるリートベルト解析法による８ａサイトに占めるリチウム含有率が９０％以上で、かつ上記リチウムマンガン複合酸化物の純度が９０％以上であることを特徴とするリチウムマンガン複合酸化物。 The following general formula (1)
Li x Mn 2-y Me y O 4-z (1)
(In the formula, Me represents a metal element or transition metal element having an atomic number of 11 or more other than manganese, x is in the range of 0 <x <2.0, and y is in the range of 0 ≦ y ≦ 0.6. Z is in the range of 0 ≦ z <2.0)
In the lithium manganese composite oxide represented by the following formula, the lithium content in the 8a site by the Rietveld analysis method by X-ray diffraction is 90% or more, and the purity of the lithium manganese composite oxide is 90% or more. A featured lithium manganese composite oxide. リチウムマンガン複合酸化物は、スピネル構造である請求項１記載のリチウムマンガン複合酸化物。   The lithium manganese composite oxide according to claim 1, wherein the lithium manganese composite oxide has a spinel structure. 請求項１又は２記載のリチウムマンガン複合酸化物を主成分として含有することを特徴とするリチウム二次電池正極活物質。   A lithium secondary battery positive electrode active material comprising the lithium manganese composite oxide according to claim 1 as a main component. 請求項３記載のリチウム二次電池正極活物質を用いたリチウム二次電池。   The lithium secondary battery using the lithium secondary battery positive electrode active material of Claim 3.
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