JP2012138197A - Positive electrode active material for lithium ion secondary battery, positive electrode, lithium ion secondary battery, and method for manufacturing positive electrode active material for lithium ion secondary battery - Google Patents
Positive electrode active material for lithium ion secondary battery, positive electrode, lithium ion secondary battery, and method for manufacturing positive electrode active material for lithium ion secondary battery Download PDFInfo
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Abstract
Description
本発明は、リチウムイオン二次電池用の正極活物質、正極、リチウムイオン二次電池、および、リチウムイオン二次電池用正極活物質の製造方法に関する。 The present invention relates to a positive electrode active material for a lithium ion secondary battery, a positive electrode, a lithium ion secondary battery, and a method for producing a positive electrode active material for a lithium ion secondary battery.
リチウムイオン二次電池は、携帯電話やノート型パソコン等の携帯型電子機器に広く用いられている。リチウムイオン二次電池用の正極活物質には、ＬｉＣｏＯ２、ＬｉＮｉＯ２、ＬｉＮｉ０．８Ｃｏ０．２Ｏ２、ＬｉＭｎＯ４等のリチウムと遷移金属等との複合酸化物が用いられている。特に、正極活物質としてＬｉＣｏＯ２を用い、リチウム合金、グラファイト、カーボンファイバー等のカーボンを負極として用いたリチウムイオン二次電池は、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。しかしながら、近年、携帯型電子機器や車載用のリチウムイオン二次電池として小型化・軽量化が求められ、単位質量あたりの放電容量、または充放電サイクルを繰り返した後に放電容量が低下しない特性（以下、サイクル特性ともいう。）の更なる向上が望まれている。 Lithium ion secondary batteries are widely used in portable electronic devices such as mobile phones and notebook computers. As a positive electrode active material for a lithium ion secondary battery, a composite oxide of lithium and a transition metal or the like such as LiCoO 2 , LiNiO 2 , LiNi 0.8 Co 0.2 O 2 , LiMnO 4 is used. In particular, a lithium ion secondary battery using LiCoO 2 as a positive electrode active material and a carbon such as a lithium alloy, graphite, or carbon fiber as a negative electrode can obtain a high voltage of 4V, so that it has a high energy density. Widely used. However, in recent years, there has been a demand for miniaturization and weight reduction as portable electronic devices and in-vehicle lithium ion secondary batteries. Further improvement of the cycle characteristics is also desired.
特許文献１には、Ｌｉ元素のモル量が遷移金属元素の総モル量に対して０．９−１．１倍モルである式ＬｉｐＮｘＭｙＯｚＦａ（０．９≦ｐ１．１）で表わされるリチウム含有複合酸化物と、ジルコニウムを含む水溶液とを撹拌、混合し、酸素雰囲気下４５０℃以上で高温焼成することにより、酸化ジルコニウムが表面層に被覆されたリチウム含有複合酸化物を得る方法が記載されている。 Patent Document 1, the formula Li p moles of Li element is 0.9-1.1 mol per mol of the total molar amount of the transition metal element N x M y O z F a (0.9 ≦ p1 .1) The lithium-containing composite oxide in which zirconium oxide is coated on the surface layer by stirring and mixing the lithium-containing composite oxide represented by (1) and an aqueous solution containing zirconium and firing at a high temperature in an oxygen atmosphere at 450 ° C. or higher. A method of obtaining an object is described.
特許文献２には、ＬｉＮｉ０．３７５Ｃｏ０．２５Ｍｎ０．３７５Ｏ２、ＬｉＮｉ０．１Ｃｏ０．８Ｍｎ０．１Ｏ２、ＬｉＮｉ１／３Ｃｏ１／３Ｍｎ１／３Ｏ２等のリチウム含有複合酸化物の粒子と、ＺｒＯ２等の電気化学的不活性な金属酸化物の粒子とを混合する正極活物質の製造方法が記載されている。該方法で得られる正極活物質は、粉体の混合物であり、実際の正極活物質中の金属酸化物の含有割合が多く、金属酸化物を多量に添加する必要があった。 Patent Document 2 includes LiNi 0.375 Co 0.25 Mn 0.375 O 2 , LiNi 0.1 Co 0.8 Mn 0.1 O 2 , LiNi 1/3 Co 1/3 Mn 1/3 O 2. A method for producing a positive electrode active material in which lithium-containing composite oxide particles such as ZrO 2 and electrochemically inactive metal oxide particles such as ZrO 2 are mixed is described. The positive electrode active material obtained by this method is a mixture of powders, and the content ratio of the metal oxide in the actual positive electrode active material is large, and it is necessary to add a large amount of metal oxide.
本発明は、サイクル特性、レート特性に優れるリチウムイオン二次電池の正極活物質、正極、リチウムイオン二次電池、および、リチウムイオン二次電池用正極活物質の製造方法を提供する。 The present invention provides a positive electrode active material for a lithium ion secondary battery excellent in cycle characteristics and rate characteristics, a positive electrode, a lithium ion secondary battery, and a method for producing a positive electrode active material for a lithium ion secondary battery.
本発明は、以下を提供する。
［１］Ｌｉ元素と、Ｎｉ、Ｃｏ、およびＭｎから選ばれる少なくとも一種の遷移金属元素とを含む（ただし、Ｌｉ元素のモル量が該遷移金属元素の総モル量に対して１．２倍超である。）リチウム含有複合酸化物の表面に、Ｚｒ、Ｔｉ、Ｓｎ、Ｍｇ、Ｂａ、Ｐｂ、Ｂｉ、Ｎｂ、Ｔａ、Ｚｎ、Ｙ、Ｌａ、Ｓｒ、Ｃｅ、ＩｎおよびＡｌから選ばれる少なくとも一種の金属元素の酸化物（Ｉ）の微粒子が付着する粒子（ＩＩ）からなることを特徴とするリチウムイオン二次電池用の正極活物質。
［２］Ｚｒ、Ｔｉ、Ｓｎ、Ｍｇ、Ｂａ、Ｐｂ、Ｂｉ、Ｎｂ、Ｔａ、Ｚｎ、Ｙ、Ｌａ、Ｓｒ、Ｃｅ、ＩｎおよびＡｌから選ばれる少なくとも一種の金属元素のモル比（被覆量）が、前記リチウム含有複合酸化物の遷移金属元素の全モル量に対して０．０００１〜０．０８倍である［１］に記載の正極活物質。
［３］前記金属元素の酸化物（Ｉ）の微粒子が、ＺｒＯ２、ＴｉＯ２、ＳｎＯ２、ＭｇＯ、ＢａＯ、ＰｂＯ、Ｂｉ２Ｏ３、Ｎｂ２Ｏ５、Ｔａ２Ｏ５、ＺｎＯ、Ｙ２Ｏ３、Ｌａ２Ｏ３、Ｓｒ２Ｏ３、ＣｅＯ２、Ｉｎ２Ｏ３、Ａｌ２Ｏ３、インジウム錫酸化物（ＩＴＯ）、イットリア安定ジルコニア（ＹＳＺ）、チタン酸金属バリウム、チタン酸ストロンチウムおよび錫酸亜鉛から選ばれる少なくとも一種である［１］または［２］に記載の正極活物質。
［４］前記リチウム含有複合酸化物が、下記式（２）で表される化合物である請求項［１］または［２］に記載の正極活物質。
Ｌｉ（ＬｉｘＭｎｙＭｅｚ）ＯｐＦｑ （２）
（但し、式（２）において、Ｍｅは、Ｃｏ、Ｎｉ、Ｃｒ、Ｆｅ、Ａｌ、Ｔｉ、Ｚｒ、Ｍｇから選ばれる少なくとも一種の元素であり、０．０９＜ｘ＜０．３、０．４≦ｙ／（ｙ＋ｚ）≦０．８、ｘ＋ｙ＋ｚ＝１、１．９＜ｐ＜２．１、０≦ｑ≦０．１である。）
［５］［１］〜［４］のいずれか一項に記載のリチウムイオン二次電池用の正極活物質と導電材とバインダーとを含むリチウムイオン二次電池用正極。
［６］［５］に記載の正極と負極と非水電解質とを含むリチウムイオン二次電池。
The present invention provides the following.
[1] Including Li element and at least one transition metal element selected from Ni, Co, and Mn (provided that the molar amount of Li element is more than 1.2 times the total molar amount of the transition metal element) At least one selected from Zr, Ti, Sn, Mg, Ba, Pb, Bi, Nb, Ta, Zn, Y, La, Sr, Ce, In, and Al on the surface of the lithium-containing composite oxide A positive electrode active material for a lithium ion secondary battery, comprising particles (II) to which fine particles of a metal element oxide (I) adhere.
[2] The molar ratio (covering amount) of at least one metal element selected from Zr, Ti, Sn, Mg, Ba, Pb, Bi, Nb, Ta, Zn, Y, La, Sr, Ce, In and Al. The positive electrode active material according to [1], which is 0.0001 to 0.08 times the total molar amount of the transition metal element of the lithium-containing composite oxide.
[3] Fine particles of the metal element oxide (I) are ZrO 2 , TiO 2 , SnO 2 , MgO, BaO, PbO, Bi 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , ZnO, Y 2. O 3 , La 2 O 3 , Sr 2 O 3 , CeO 2 , In 2 O 3 , Al 2 O 3 , indium tin oxide (ITO), yttria stable zirconia (YSZ), metal barium titanate, strontium titanate and The positive electrode active material according to [1] or [2], which is at least one selected from zinc stannate.
[4] The positive electrode active material according to [1] or [2], wherein the lithium-containing composite oxide is a compound represented by the following formula (2).
Li (Li x Mn y Me z ) O p F q (2)
(In the formula (2), Me is at least one element selected from Co, Ni, Cr, Fe, Al, Ti, Zr, and Mg, and 0.09 <x <0.3, 0.4 ≦ y / (y + z) ≦ 0.8, x + y + z = 1, 1.9 <p <2.1, 0 ≦ q ≦ 0.1.
[5] A positive electrode for a lithium ion secondary battery comprising the positive electrode active material for a lithium ion secondary battery according to any one of [1] to [4], a conductive material, and a binder.
[6] A lithium ion secondary battery including the positive electrode, the negative electrode, and a nonaqueous electrolyte according to [5].
［７］Ｌｉ元素と、Ｎｉ、ＣｏおよびＭｎから選ばれる少なくとも一種の遷移金属元素とを含む（ただし、Ｌｉ元素のモル量が該遷移金属元素の総モル量に対して１．２倍超である。）リチウム含有複合酸化物と、下記組成物（１）とを接触させて、加熱することにより、前記リチウム含有複合酸化物の表面にＺｒ、Ｔｉ、Ｓｎ、Ｍｇ、Ｂａ、Ｐｂ、Ｂｉ、Ｎｂ、Ｔａ、Ｚｎ、Ｙ、Ｌａ、Ｓｒ、Ｃｅ、ＩｎおよびＡｌから選ばれる少なくとも一種の金属元素の酸化物（Ｉ）の微粒子が付着する粒子（ＩＩ）からなるリチウムイオン二次電池用正極活物質を得ることを特徴とする、リチウムイオン二次電池用正極活物質の製造方法。
組成物（１）：Ｚｒ、Ｔｉ、Ｓｎ、Ｍｇ、Ｂａ、Ｐｂ、Ｂｉ、Ｎｂ、Ｔａ、Ｚｎ、Ｙ、Ｌａ、Ｓｒ、Ｃｅ、ＩｎおよびＡｌから選ばれる少なくとも一種の金属元素の酸化物（Ｉ）の微粒子を溶媒に分散させた分散液。
［８］前記酸化物（Ｉ）の微粒子が、ＺｒＯ２、ＴｉＯ２、ＳｎＯ２、ＭｇＯ、ＢａＯ、ＰｂＯ、Ｂｉ２Ｏ３、Ｎｂ２Ｏ５、Ｔａ２Ｏ５、ＺｎＯ、Ｙ２Ｏ３、Ｌａ２Ｏ３、Ｓｒ２Ｏ３、ＣｅＯ２、Ｉｎ２Ｏ３、Ａｌ２Ｏ３、インジウム錫酸化物（ＩＴＯ）、イットリア安定ジルコニア（ＹＳＺ）、チタン酸金属バリウム、チタン酸ストロンチウムおよび錫酸亜鉛から選ばれる少なくとも一種である［７］に記載の製造方法。
［９］前記加熱を５０〜３５０℃で行う［７］または［８］に記載の製造方法。
［１０］前記組成物（１）の溶媒が、水である［７］〜［９］のいずれか一項に記載の製造方法。
［１１］前記組成物（１）のｐＨが、３〜１２である［７］〜［１０］のいずれか一項に記載の製造方法。
［１２］前記リチウム含有複合酸化物と、前記組成物（１）との接触を、撹拌しているリチウム含有複合酸化物に該組成物を添加して、前記リチウム含有複合酸化物と該組成物とを混合することにより行う、［７］〜［１１］のいずれか一項に記載の製造方法。
［１３］前記リチウム含有複合酸化物と、前記組成物（１）との接触を、スプレーコート法によって該組成物を前記リチウム含有複合酸化物に噴霧することにより行う、［７］〜［１２］のいずれか一項に記載の製造方法。
[7] Including Li element and at least one transition metal element selected from Ni, Co and Mn (provided that the molar amount of Li element is more than 1.2 times the total molar amount of the transition metal element) The lithium-containing composite oxide is brought into contact with the following composition (1) and heated to bring Zr, Ti, Sn, Mg, Ba, Pb, Bi, Positive electrode active for lithium ion secondary battery comprising particles (II) to which fine particles of oxide (I) of at least one metal element selected from Nb, Ta, Zn, Y, La, Sr, Ce, In and Al are attached A method for producing a positive electrode active material for a lithium ion secondary battery, wherein the material is obtained.
Composition (1): oxide of at least one metal element selected from Zr, Ti, Sn, Mg, Ba, Pb, Bi, Nb, Ta, Zn, Y, La, Sr, Ce, In and Al (I ) In a solvent.
[8] The fine particles of the oxide (I) are ZrO 2 , TiO 2 , SnO 2 , MgO, BaO, PbO, Bi 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , ZnO, Y 2 O 3 , La 2 O 3 , Sr 2 O 3 , CeO 2 , In 2 O 3 , Al 2 O 3 , indium tin oxide (ITO), yttria stable zirconia (YSZ), metal barium titanate, strontium titanate and zinc stannate The production method according to [7], which is at least one selected from the group consisting of:
[9] The production method according to [7] or [8], wherein the heating is performed at 50 to 350 ° C.
[10] The production method according to any one of [7] to [9], wherein the solvent of the composition (1) is water.
[11] The production method according to any one of [7] to [10], wherein the pH of the composition (1) is 3 to 12.
[12] The lithium-containing composite oxide and the composition are added to the lithium-containing composite oxide stirring the contact between the lithium-containing composite oxide and the composition (1). The production method according to any one of [7] to [11], which is carried out by mixing.
[13] The contact between the lithium-containing composite oxide and the composition (1) is performed by spraying the composition onto the lithium-containing composite oxide by a spray coating method. [7] to [12] The manufacturing method as described in any one of these.
本発明の正極活物質は、サイクル特性、レート特性に優れる。本発明の正極およびリチウムイオン二次電池は、サイクル特性、レート特性に優れる。さらに、本発明の製造方法は、サイクル特性、レート特性に優れる正極活物質、正極およびリチウムイオン二次電池を製造することができる。 The positive electrode active material of the present invention is excellent in cycle characteristics and rate characteristics. The positive electrode and the lithium ion secondary battery of the present invention are excellent in cycle characteristics and rate characteristics. Furthermore, the production method of the present invention can produce a positive electrode active material, a positive electrode, and a lithium ion secondary battery that are excellent in cycle characteristics and rate characteristics.
＜正極活物質＞
本発明の正極活物質は、Ｌｉ元素と、Ｎｉ、ＣｏおよびＭｎから選ばれる少なくとも一種の遷移金属元素とを含む（ただし、Ｌｉ元素のモル量が該遷移金属元素の総モル量に対して１．２倍超である。）リチウム含有複合酸化物の表面に、Ｚｒ、Ｔｉ、Ｓｎ、Ｍｇ、Ｂａ、Ｐｂ、Ｂｉ、Ｎｂ、Ｔａ、Ｚｎ、Ｙ、Ｌａ、Ｓｒ、Ｃｅ、ＩｎおよびＡｌから選ばれる少なくとも一種の金属元素の酸化物（Ｉ）の微粒子が付着する粒子（ＩＩ）からなることを特徴とする。
<Positive electrode active material>
The positive electrode active material of the present invention contains Li element and at least one transition metal element selected from Ni, Co and Mn (provided that the molar amount of Li element is 1 with respect to the total molar amount of the transition metal element). More than 2 times.) The surface of the lithium-containing composite oxide is selected from Zr, Ti, Sn, Mg, Ba, Pb, Bi, Nb, Ta, Zn, Y, La, Sr, Ce, In, and Al. It is characterized by comprising particles (II) to which fine particles of at least one metal element oxide (I) are adhered.
（リチウム含有複合酸化物）
本発明におけるリチウム含有複合酸化物は、Ｌｉ元素と、Ｎｉ、ＣｏおよびＭｎから選ばれる少なくとも一種の遷移金属元素とを含むものであって、Ｌｉ元素のモル量が該遷移金属元素の総モル量に対して１．２倍モル超｛すなわち、（Ｌｉ元素のモル量／遷移金属元素の総モル量）＞１．２｝である。Ｌｉ元素のモル量が該遷移金属元素の総モル量に対して１．２倍超であると、単位質量あたりの放電容量を向上させることができる。
(Lithium-containing composite oxide)
The lithium-containing composite oxide in the present invention contains Li element and at least one transition metal element selected from Ni, Co and Mn, and the molar amount of Li element is the total molar amount of the transition metal element. More than 1.2 times the molar amount {namely, (the molar amount of Li element / the total molar amount of transition metal element)> 1.2}. When the molar amount of Li element is more than 1.2 times the total molar amount of the transition metal element, the discharge capacity per unit mass can be improved.
Ｌｉ元素の前記遷移金属元素の総モル量に対する組成比は、単位質量あたりの放電容量をより一層増加させるために１．２５〜１．７５であることが好ましく、１．２５〜１．６５であることがより好ましい。 The composition ratio of Li element to the total molar amount of the transition metal element is preferably 1.25 to 1.75 in order to further increase the discharge capacity per unit mass, More preferably.
遷移金属元素としては、Ｎｉ、ＣｏおよびＭｎから選ばれる少なくとも一種の元素を含むのが好ましく、Ｍｎ元素を必須とするのが特に好ましく、Ｎｉ、Ｃｏ、およびＭｎを含むのがとりわけ好ましい。さらに、遷移金属元素としては、Ｎｉ、ＣｏおよびＭｎ以外の元素（以下、他の遷移金属元素と記す。）を必要に応じて含むのが好ましく、該他の遷移金属元素としては、Ｃｒ、Ｆｅ、Ａｌ、Ｔｉ、Ｚｒ、およびＭｇ等が挙げられる。
本発明におけるリチウム含有複合酸化物として、下記式（２）で表される化合物が好ましい。下記式（２）で表される化合物は、充放電や活性化等の処理を行う前の組成である。ここで、活性化とは、電池として通常４．４Ｖもしくは４．６Ｖ（ｖｓ．Ｌｉ０）より大きな電位で電気化学的に、または、硫酸、塩酸もしくは硝酸のような酸を用いた化学反応により、化学的に、酸化リチウム（Ｌｉ２Ｏ）、または、リチウムおよび酸化リチウムを、リチウム含有複合酸化物から取り除くことをいう。
The transition metal element preferably includes at least one element selected from Ni, Co, and Mn, particularly preferably includes the Mn element, and particularly preferably includes Ni, Co, and Mn. Further, as the transition metal element, it is preferable to contain an element other than Ni, Co and Mn (hereinafter referred to as other transition metal element) as necessary, and as the other transition metal element, Cr, Fe , Al, Ti, Zr, and Mg.
As a lithium containing complex oxide in this invention, the compound represented by following formula (2) is preferable. The compound represented by the following formula (2) has a composition before performing treatments such as charge / discharge and activation. Here, the activation is usually electrochemical at a potential higher than 4.4V or 4.6V (vs. Li 0 ) as a battery, or by a chemical reaction using an acid such as sulfuric acid, hydrochloric acid or nitric acid. Chemically refers to removing lithium oxide (Li 2 O) or lithium and lithium oxide from the lithium-containing composite oxide.
Ｌｉ（ＬｉｘＭｎｙＭｅｚ）ＯｐＦｑ （２）
式（２）において、Ｍｅは、Ｃｏ、Ｎｉ、Ｃｒ、Ｆｅ、Ａｌ、Ｔｉ、Ｚｒ、Ｍｇから選ばれる少なくとも一種の元素である。式（２）においては、０．０９＜ｘ＜０．３、０．４≦ｙ／（ｙ＋ｚ）≦０．８、ｘ＋ｙ＋ｚ＝１、１．９＜ｐ＜２．１、０≦ｑ≦０．１である。Ｍｅとしては、Ｃｏ、Ｎｉ、Ｃｒが好ましく、Ｃｏ、Ｎｉが特に好ましい。一般式（２）においては、０．１＜ｘ＜０．２５が好ましく、０．１１＜ｘ＜０．２２がより好ましく、０．５≦ｙ／（ｙ＋ｚ）≦０．８が好ましく、０．５５≦ｙ／（ｙ＋ｚ）≦０．７５がより好ましい。
Li (Li x Mn y Me z ) O p F q (2)
In the formula (2), Me is at least one element selected from Co, Ni, Cr, Fe, Al, Ti, Zr, and Mg. In the formula (2), 0.09 <x <0.3, 0.4 ≦ y / (y + z) ≦ 0.8, x + y + z = 1, 1.9 <p <2.1, 0 ≦ q ≦ 0 .1. As Me, Co, Ni, and Cr are preferable, and Co and Ni are particularly preferable. In the general formula (2), 0.1 <x <0.25 is preferable, 0.11 <x <0.22 is more preferable, 0.5 ≦ y / (y + z) ≦ 0.8 is preferable, and 0 .55 ≦ y / (y + z) ≦ 0.75 is more preferable.
リチウム含有複合酸化物の具体例としては、Ｌｉ（Ｌｉ０．１３０Ｎｉ０．２６Ｃｏ０．０９Ｍｎ０．５２）Ｏ２、Ｌｉ（Ｌｉ０．１３Ｎｉ０．２２Ｃｏ０．０９Ｍｎ０．５６）Ｏ２、Ｌｉ（Ｌｉ０．１３Ｎｉ０．１７Ｃｏ０．１７Ｍｎ０．５３）Ｏ２、Ｌｉ（Ｌｉ０．１５Ｎｉ０．１７Ｃｏ０．１３Ｍｎ０．５５）Ｏ２、Ｌｉ（Ｌｉ０．１６Ｎｉ０．１７Ｃｏ０．０８Ｍｎ０．５９）Ｏ２、Ｌｉ（Ｌｉ０．１７Ｎｉ０．１７Ｃｏ０．１７Ｍｎ０．４９）Ｏ２、Ｌｉ（Ｌｉ０．１７Ｎｉ０．２１Ｃｏ０．０８Ｍｎ０．５４）Ｏ２、Ｌｉ（Ｌｉ０．１７Ｎｉ０．１４Ｃｏ０．１４Ｍｎ０．５５）Ｏ２、Ｌｉ（Ｌｉ０．１８Ｎｉ０．１２Ｃｏ０．１２Ｍｎ０．５８）Ｏ２、Ｌｉ（Ｌｉ０．１８Ｎｉ０．１６Ｃｏ０．１２Ｍｎ０．５４）Ｏ２、Ｌｉ（Ｌｉ０．２０Ｎｉ０．１２Ｃｏ０．０８Ｍｎ０．６０）Ｏ２、Ｌｉ（Ｌｉ０．２０Ｎｉ０．１６Ｃｏ０．０８Ｍｎ０．５６）Ｏ２、Ｌｉ（Ｌｉ０．２０Ｎｉ０．１３Ｃｏ０．１３Ｍｎ０．５４）Ｏ２、Ｌｉ（Ｌｉ０．２２Ｎｉ０．１２Ｃｏ０．１２Ｍｎ０．５４）Ｏ２、Ｌｉ（Ｌｉ０．２３Ｎｉ０．１２Ｃｏ０．０８Ｍｎ０．５７）Ｏ２、が好ましく、Ｌｉ（Ｌｉ０．１６Ｎｉ０．１７Ｃｏ０．０８Ｍｎ０．５９）Ｏ２、Ｌｉ（Ｌｉ０．１７Ｎｉ０．１７Ｃｏ０．１７Ｍｎ０．４９）Ｏ２、Ｌｉ（Ｌｉ０．１７Ｎｉ０．２１Ｃｏ０．０８Ｍｎ０．５４）Ｏ２、Ｌｉ（Ｌｉ０．１７Ｎｉ０．１４Ｃｏ０．１４Ｍｎ０．５５）Ｏ２、Ｌｉ（Ｌｉ０．１８Ｎｉ０．１２Ｃｏ０．１２Ｍｎ０．５８）Ｏ２、Ｌｉ（Ｌｉ０．１８Ｎｉ０．１６Ｃｏ０．１２Ｍｎ０．５４）Ｏ２、Ｌｉ（Ｌｉ０．２０Ｎｉ０．１２Ｃｏ０．０８Ｍｎ０．６０）Ｏ２、Ｌｉ（Ｌｉ０．２０Ｎｉ０．１６Ｃｏ０．０８Ｍｎ０．５６）Ｏ２、Ｌｉ（Ｌｉ０．２０Ｎｉ０．１３Ｃｏ０．１３Ｍｎ０．５４）Ｏ２、が挙げられる。 Specific examples of the lithium-containing composite oxide include Li (Li 0.130 Ni 0.26 Co 0.09 Mn 0.52 ) O 2 , Li (Li 0.13 Ni 0.22 Co 0.09 Mn 0. 56 ) O 2 , Li (Li 0.13 Ni 0.17 Co 0.17 Mn 0.53 ) O 2 , Li (Li 0.15 Ni 0.17 Co 0.13 Mn 0.55 ) O 2 , Li (Li 0.16 Ni 0.17 Co 0.08 Mn 0.59 ) O 2 , Li (Li 0.17 Ni 0.17 Co 0.17 Mn 0.49 ) O 2 , Li (Li 0.17 Ni 0.21 Co 0.08 Mn 0.54 ) O 2 , Li (Li 0.17 Ni 0.14 Co 0.14 Mn 0.55 ) O 2 , Li (Li 0.18 Ni 0.12 Co 0. 12 Mn 0.58) O 2, Li ( i 0.18 Ni 0.16 Co 0.12 Mn 0.54 ) O 2, Li (Li 0.20 Ni 0.12 Co 0.08 Mn 0.60) O 2, Li (Li 0.20 Ni 0 .16 Co 0.08 Mn 0.56 ) O 2 , Li (Li 0.20 Ni 0.13 Co 0.13 Mn 0.54 ) O 2 , Li (Li 0.22 Ni 0.12 Co 0.12 Mn 0.54 ) O 2 , Li (Li 0.23 Ni 0.12 Co 0.08 Mn 0.57 ) O 2 , and Li (Li 0.16 Ni 0.17 Co 0.08 Mn 0. 59) O 2, Li (Li 0.17 Ni 0.17 Co 0.17 Mn 0.49) O 2, Li (Li 0.17 Ni 0.21 Co 0.08 Mn 0.54) O 2, Li (Li 0.17 Ni 0.14 Co 0.1 4 Mn 0.55 ) O 2 , Li (Li 0.18 Ni 0.12 Co 0.12 Mn 0.58 ) O 2 , Li (Li 0.18 Ni 0.16 Co 0.12 Mn 0.54 ) O 2 , Li (Li 0.20 Ni 0.12 Co 0.08 Mn 0.60 ) O 2 , Li (Li 0.20 Ni 0.16 Co 0.08 Mn 0.56 ) O 2 , Li (Li 0.20 Ni 0.13 Co 0.13 Mn 0.54 ) O 2 .
本発明におけるリチウム含有複合酸化物が、上記式（２）で表される化合物である場合、Ｌｉ元素のモル量の前記遷移金属元素の総モル量に対する組成比｛すなわち、（１＋ｘ）／（ｙ＋ｚ）｝は１．２倍超であり、１．２５〜１．７５倍が好ましく、１．２５〜１．６５倍がより好ましい。該組成比が上記の範囲であれば、単位質量あたりの放電容量を増加させることができる。 When the lithium-containing composite oxide in the present invention is a compound represented by the above formula (2), the composition ratio of the molar amount of Li element to the total molar amount of the transition metal element {ie, (1 + x) / (y + z) )} Is more than 1.2 times, preferably 1.25 to 1.75 times, more preferably 1.25 to 1.65 times. When the composition ratio is in the above range, the discharge capacity per unit mass can be increased.
リチウム含有複合酸化物は、粒子状であることが好ましく、平均粒子径Ｄ５０は３〜３０μｍが好ましく、４〜２５μｍがより好ましく、５〜２０μｍが特に好ましい。本発明において、平均粒子径Ｄ５０とは、体積基準で粒度分布を求め、全体積を１００％とした累積カーブにおいて、その累積カーブが５０％となる点の粒子径である、体積基準累積５０％径（Ｄ５０）を意味する。粒度分布は、レーザー散乱粒度分布測定装置で測定した頻度分布および累積体積分布曲線で求められる。粒子径の測定は、粉末を水媒体中に超音波処理等で充分に分散させて粒度分布を測定する（例えば、ＨＯＲＩＢＡ社製レーザー回折／散乱式粒子径分布測定装置Ｐａｒｔｉｃａ ＬＡ−９５０ＶＩＩ、等を用いる）ことで行なわれる。 The lithium-containing composite oxide is preferably particulate, and the average particle diameter D50 is preferably 3 to 30 μm, more preferably 4 to 25 μm, and particularly preferably 5 to 20 μm. In the present invention, the average particle diameter D50 is a particle diameter at a point at which the cumulative curve is 50% in a cumulative curve obtained by obtaining a particle size distribution on a volume basis and setting the total volume to 100%. It means the diameter (D50). The particle size distribution is obtained from a frequency distribution and a cumulative volume distribution curve measured with a laser scattering particle size distribution measuring apparatus. The particle size is measured by sufficiently dispersing the powder in an aqueous medium by ultrasonic treatment or the like, and measuring the particle size distribution (for example, using a laser diffraction / scattering particle size distribution measuring device Partica LA-950VII manufactured by HORIBA). Used).
リチウム含有複合酸化物の比表面積は、０．３〜１０ｍ２／ｇであることが好ましく、０．５〜５ｍ２／ｇが特に好ましい。該比表面積が、０．３〜１０ｍ２／ｇであると容量が高く、緻密な正極電極層が形成できる。なお、比表面積は、窒素を用いたＢＥＴ法で測定することが好ましい。
本発明におけるリチウム含有複合酸化物は、層状岩塩型結晶構造（空間群Ｒ−３ｍ）をとるものであることが好ましい。また、本発明におけるリチウム含有複合酸化物は、遷移金属元素に対するＬｉ元素の比率が高いため、ＸＲＤ（Ｘ線回折）測定では層状Ｌｉ２ＭｎＯ３と同様に２θ＝２０〜２５°の範囲にピークが観察される。
The specific surface area of the lithium-containing composite oxide is preferably 0.3~10m 2 / g, 0.5~5m 2 / g is particularly preferred. When the specific surface area is 0.3 to 10 m 2 / g, the capacity is high and a dense positive electrode layer can be formed. The specific surface area is preferably measured by the BET method using nitrogen.
The lithium-containing composite oxide in the present invention preferably has a layered rock salt type crystal structure (space group R-3m). In addition, since the lithium-containing composite oxide in the present invention has a high ratio of Li element to transition metal element, XRD (X-ray diffraction) measurement shows a peak in the range of 2θ = 20 to 25 ° as in the case of layered Li 2 MnO 3. Is observed.
（酸化物（Ｉ）の微粒子）
本発明における酸化物（Ｉ）の微粒子は、Ｚｒ、Ｔｉ、Ｓｎ、Ｍｇ、Ｂａ、Ｐｂ、Ｂｉ、Ｎｂ、Ｔａ、Ｚｎ、Ｙ、Ｌａ、Ｓｒ、Ｃｅ、ＩｎおよびＡｌから選ばれる少なくとも一種の金属元素の酸化物である。該酸化物は、電圧での充電（酸化反応）によって生じる電解質の分解によって生じた分解物との接触を防ぐため、分解物と不活性な化合物であることが好ましい。
酸化物（Ｉ）の微粒子は、ＺｒＯ２、ＴｉＯ２、ＳｎＯ２、ＭｇＯ、ＢａＯ、ＰｂＯ、Ｂｉ２Ｏ３、Ｎｂ２Ｏ５、Ｔａ２Ｏ５、ＺｎＯ、Ｙ２Ｏ３、Ｌａ２Ｏ３、Ｓｒ２Ｏ３、ＣｅＯ２、Ｉｎ２Ｏ３、Ａｌ２Ｏ３、インジウム錫酸化物（ＩＴＯ）、イットリア安定ジルコニア（ＹＳＺ）、チタン酸金属バリウム、チタン酸ストロンチウムおよび錫酸亜鉛等が好ましい。
酸化物（Ｉ）の微粒子は、均一な被膜が得られやすく、化学的に安定であることから、Ｚｒ元素を含む酸化物が好ましく、特にＺｒＯ２が好ましい。
(Fine particles of oxide (I))
The fine particles of oxide (I) in the present invention are at least one metal selected from Zr, Ti, Sn, Mg, Ba, Pb, Bi, Nb, Ta, Zn, Y, La, Sr, Ce, In, and Al. It is an oxide of an element. The oxide is preferably an inactive compound with the decomposition product in order to prevent contact with the decomposition product generated by the decomposition of the electrolyte generated by charging with voltage (oxidation reaction).
The fine particles of oxide (I) are ZrO 2 , TiO 2 , SnO 2 , MgO, BaO, PbO, Bi 2 O 3 , Nb 2 O 5 , Ta 2 O 5 , ZnO, Y 2 O 3 , La 2 O 3. Sr 2 O 3 , CeO 2 , In 2 O 3 , Al 2 O 3 , indium tin oxide (ITO), yttria stable zirconia (YSZ), metal barium titanate, strontium titanate and zinc stannate are preferable.
The oxide (I) fine particles are preferably an oxide containing a Zr element, particularly ZrO 2 , since a uniform film is easily obtained and is chemically stable.
酸化物（Ｉ）の微粒子の形状は、ＳＥＭ（走査形電子顕微鏡）、ＴＥＭ（透過型電子顕微鏡）等の電子顕微鏡により評価することができる。酸化物（Ｉ）の微粒子の形状は、粒子状、膜状、塊状等であってもよい。酸化物（Ｉ）の微粒子が粒子状である場合、酸化物（Ｉ）の微粒子の平均粒子径は、１〜１００ｎｍが好ましく、２〜５０ｎｍがより好ましく、３〜３０ｎｍが特に好ましい。酸化物（Ｉ）の微粒子の平均粒子径は、ＳＥＭ、ＴＥＭ等の電子顕微鏡より観察される、リチウム含有複合酸化物の表面を被覆している粒子の粒子径の平均である。 The shape of the oxide (I) fine particles can be evaluated by an electron microscope such as SEM (scanning electron microscope) or TEM (transmission electron microscope). The shape of the fine particles of the oxide (I) may be a particle shape, a film shape, a lump shape, or the like. When the oxide (I) fine particles are in the form of particles, the average particle size of the oxide (I) fine particles is preferably 1 to 100 nm, more preferably 2 to 50 nm, and particularly preferably 3 to 30 nm. The average particle diameter of the fine particles of the oxide (I) is an average particle diameter of the particles covering the surface of the lithium-containing composite oxide, which is observed with an electron microscope such as SEM or TEM.
（粒子（ＩＩ））
本発明における粒子（ＩＩ）は、上記リチウム含有複合酸化物の表面に上記酸化物（Ｉ）の微粒子が付着するものである。ここで、付着するとは、リチウム含有複合酸化物の表面に、酸化物（Ｉ）の微粒子が物理吸着、あるいは化学吸着している状態をいう。前記粒子（ＩＩ）において、酸化物（Ｉ）の微粒子がリチウム含有複合酸化物の表面に付着していることは、例えば、粒子（ＩＩ）を切断した後に断面を研磨し、Ｘ線マイクロアナライザー分析法（ＥＰＭＡ）で元素マッピングを行うことにより評価することができる。該評価方法によって、前記酸化物（Ｉ）がリチウム含有複合酸化物の中心（ここで、中心とは、リチウム含有複合酸化物の表面に接していない部分をいい、表面からの平均距離が最長である部分であるのが好ましい。）に対して、表面から１００ｎｍの範囲により多く存在することが確認できる。
粒子（ＩＩ）における酸化物（Ｉ）の微粒子の割合は、正極活物質を酸に溶解してＩＣＰ（高周波誘導結合プラズマ）測定により求めることができる。ＩＣＰ測定によって酸化物（Ｉ）の微粒子の割合を求めることができない場合には、リチウム含有複合粒子と酸化物（Ｉ）の微粒子の仕込み量に基づいて算出されうる値である。
(Particle (II))
The particles (II) in the present invention are those in which the fine particles of the oxide (I) adhere to the surface of the lithium-containing composite oxide. Here, adhering means a state in which fine particles of oxide (I) are physically adsorbed or chemically adsorbed on the surface of the lithium-containing composite oxide. In the particles (II), the fine particles of the oxide (I) are adhered to the surface of the lithium-containing composite oxide. For example, after the particles (II) are cut, the cross section is polished and analyzed by X-ray microanalyzer. It can be evaluated by performing element mapping by the method (EPMA). According to the evaluation method, the oxide (I) is the center of the lithium-containing composite oxide (here, the center is a portion not in contact with the surface of the lithium-containing composite oxide, and the average distance from the surface is the longest). On the other hand, it can be confirmed that there is more in the range of 100 nm from the surface.
The proportion of the oxide (I) fine particles in the particles (II) can be determined by ICP (high frequency inductively coupled plasma) measurement by dissolving the positive electrode active material in an acid. When the ratio of oxide (I) fine particles cannot be determined by ICP measurement, the value can be calculated based on the charged amounts of lithium-containing composite particles and oxide (I) fine particles.
粒子（ＩＩ）における酸化物（Ｉ）の微粒子の割合は、酸化物（Ｉ）の微粒子中のＺｒ、Ｔｉ、Ｓｎ、Ｍｇ、Ｂａ、Ｐｂ、Ｂｉ、Ｎｂ、Ｔａ、Ｚｎ、Ｙ、Ｌａ、Ｓｒ、Ｃｅ、ＩｎおよびＡｌから選ばれる少なくとも一種の金属元素のモル比（被覆量）がリチウム含有複合酸化物の遷移金属元素の全モル量に対して０．０００１〜０．０８倍であることが好ましく、０．０００３〜０．０４倍であることがより好ましく、０．０００５〜０．０３倍であることが特に好ましい。上述の範囲であれば、リチウム含有複合酸化物と電解質の分解によって生じた分解物との接触を防ぐことができる。 The ratio of the fine particles of the oxide (I) in the particles (II) is Zr, Ti, Sn, Mg, Ba, Pb, Bi, Nb, Ta, Zn, Y, La, Sr in the fine particles of the oxide (I). The molar ratio (covering amount) of at least one metal element selected from Ce, In, and Al is 0.0001 to 0.08 times the total molar amount of transition metal elements of the lithium-containing composite oxide. Preferably, it is 0.0003 to 0.04 times, more preferably 0.0005 to 0.03 times. If it is the above-mentioned range, a contact with the decomposition product produced by decomposition | disassembly of lithium containing complex oxide and electrolyte can be prevented.
酸化物（Ｉ）の微粒子はリチウム含有複合酸化物の表面に付着する。酸化物（Ｉ）の微粒子は、リチウム含有複合酸化物の表面の全部を被覆していても、一部を被覆していてもよい。
本発明の正極活物質は、リチウム比率の高いリチウム含有複合酸化物を用いているため放電容量が大きい。また、本発明の正極活物質は、リチウム含有複合酸化物の表面にＺｒ、Ｔｉ、Ｓｎ、Ｍｇ、Ｂａ、Ｐｂ、Ｂｉ、Ｎｂ、Ｔａ、Ｚｎ、Ｙ、Ｌａ、Ｓｒ、Ｃｅ、ＩｎおよびＡｌから選ばれる少なくとも一種の金属元素の酸化物（Ｉ）の微粒子が付着している粒子（ＩＩ）からなるものであるため、特にＭｎ元素の溶出が抑制され、高電圧（特に４．５Ｖ以上）で充放電サイクルを行っても容量の低下が少なく、サイクル特性に優れる。
Fine particles of the oxide (I) adhere to the surface of the lithium-containing composite oxide. The fine particles of the oxide (I) may cover the entire surface of the lithium-containing composite oxide or may partially cover it.
Since the positive electrode active material of the present invention uses a lithium-containing composite oxide having a high lithium ratio, the discharge capacity is large. Moreover, the positive electrode active material of the present invention is formed on the surface of the lithium-containing composite oxide from Zr, Ti, Sn, Mg, Ba, Pb, Bi, Nb, Ta, Zn, Y, La, Sr, Ce, In, and Al. Since it is composed of particles (II) to which fine particles of oxide (I) of at least one selected metal element are adhered, elution of Mn element is suppressed particularly, and at a high voltage (especially 4.5 V or more). Even when a charge / discharge cycle is performed, the capacity is hardly reduced and the cycle characteristics are excellent.
＜正極活物質の製造方法＞
本発明のリチウムイオン二次電池用正極活物質の製造方法は、Ｌｉ元素と、Ｎｉ、Ｃｏ、およびＭｎから選ばれる少なくとも一種の遷移金属元素とを含む（ただし、Ｌｉ元素のモル量が該遷移金属元素の総モル量に対して１．２倍超である。）リチウム含有複合酸化物と、下記組成物（１）とを接触させて、加熱することにより前記リチウム含有複合酸化物の表面にＺｒ、Ｔｉ、Ｓｎ、Ｍｇ、Ｂａ、Ｐｂ、Ｂｉ、Ｎｂ、Ｔａ、Ｚｎ、Ｙ、Ｌａ、Ｓｒ、Ｃｅ、ＩｎおよびＡｌから選ばれる少なくとも一種の金属元素の酸化物（Ｉ）の微粒子が付着する粒子（ＩＩ）からなるリチウムイオン二次電池用正極活物質を得る方法である。
<Method for producing positive electrode active material>
The method for producing a positive electrode active material for a lithium ion secondary battery of the present invention contains Li element and at least one transition metal element selected from Ni, Co, and Mn (provided that the molar amount of Li element is the transition element). More than 1.2 times the total molar amount of the metal elements.) The lithium-containing composite oxide is brought into contact with the following composition (1) and heated to bring the surface of the lithium-containing composite oxide onto the surface. Fine particles of oxide (I) of at least one metal element selected from Zr, Ti, Sn, Mg, Ba, Pb, Bi, Nb, Ta, Zn, Y, La, Sr, Ce, In, and Al are attached. This is a method of obtaining a positive electrode active material for lithium ion secondary batteries comprising particles (II).
組成物（１）：Ｚｒ、Ｔｉ、Ｓｎ、Ｍｇ、Ｂａ、Ｐｂ、Ｂｉ、Ｎｂ、Ｔａ、Ｚｎ、Ｙ、Ｌａ、Ｓｒ、Ｃｅ、ＩｎおよびＡｌから選ばれる少なくとも一種の金属元素の酸化物（Ｉ）の微粒子を溶媒に分散させた分散液。
リチウム含有複合酸化物としては、上記のリチウム含有複合酸化物を用いることができ、好ましい態様も同様である。
Composition (1): oxide of at least one metal element selected from Zr, Ti, Sn, Mg, Ba, Pb, Bi, Nb, Ta, Zn, Y, La, Sr, Ce, In and Al (I ) In a solvent.
As the lithium-containing composite oxide, the above-described lithium-containing composite oxide can be used, and the preferred embodiment is also the same.
リチウム含有複合酸化物の製造方法としては、共沈法により得られたリチウム含有複合酸化物の前躯体とリチウム化合物を混合して焼成する方法、水熱合成法、ゾルゲル法、乾式混合法、イオン交換法等が挙げられるが、含有される遷移金属元素が均一に混ざることで放電容量が優れるため、共沈法により得られたリチウム含有複合酸化物の前躯体（共沈組成物）とリチウム化合物を混合して焼成する方法が好ましい。 As a method for producing a lithium-containing composite oxide, a method of mixing and baking a precursor of a lithium-containing composite oxide obtained by a coprecipitation method and a lithium compound, a hydrothermal synthesis method, a sol-gel method, a dry mixing method, an ion The exchange method etc. are mentioned, but the discharge capacity is excellent because the transition metal elements contained are uniformly mixed, so the precursor (coprecipitation composition) of lithium-containing composite oxide obtained by the coprecipitation method and the lithium compound The method of mixing and baking is preferable.
組成物（１）は、Ｚｒ、Ｔｉ、Ｓｎ、Ｍｇ、Ｂａ、Ｐｂ、Ｂｉ、Ｎｂ、Ｔａ、Ｚｎ、Ｙ、Ｌａ、Ｓｒ、Ｃｅ、ＩｎおよびＡｌから選ばれる少なくとも一種の金属元素の酸化物（Ｉ）の微粒子を溶媒に分散させた分散液である。酸化物（Ｉ）の微粒子としては、上記の酸化物（Ｉ）の微粒子を用いることができ、好ましい態様も同様である。 The composition (1) is an oxide of at least one metal element selected from Zr, Ti, Sn, Mg, Ba, Pb, Bi, Nb, Ta, Zn, Y, La, Sr, Ce, In, and Al ( It is a dispersion liquid in which fine particles of I) are dispersed in a solvent. As the fine particles of the oxide (I), the fine particles of the oxide (I) can be used, and the preferred embodiment is also the same.
溶媒としては、金属元素を含む化合物の安定性や反応性の点で水を含む溶媒が好ましく、水と水溶性アルコールおよび／またはポリオールとの混合溶媒がより好ましく、水が特に好ましい。水溶性アルコールとしては、メタノール、エタノール、１−プロパノール、２−プロパノールが挙げられる。ポリオールとしては、エチレングリコール、プロピレングリコール、ジエチレングリコール、ジプロピレングリコール、ポリエチレングリコール、ブタンジオール、グリセリンが挙げられる。溶媒中に含まれる水溶性アルコールとポリオールの合計の含有量としては、各溶媒の合計量（溶媒全量）に対して０〜２０質量％が好ましく、０〜１０質量％がより好ましい。溶媒が水だけの場合は、安全面、環境面、取扱い性、コストの点で優れているため特に好ましい。
組成物（１）に含まれる酸化物（Ｉ）の微粒子の動的光散乱径は、１〜１００ｎｍであることが好ましく、２〜５０ｎｍであればさらに好ましく、３〜３０ｎｍであれば特に好ましい。動的光散乱径とは、動的光散乱法により測定した粒子のメディアン径であり、酸化物（Ｉ）の微粒子を溶媒に分散させた状態で測定する（例えば、日機装社製ナノトラックＵＰＡを用いる。）。粒子径が１ｎｍ以上であれば、不純物が少なく、安定した分散液が得られやすい。粒子径が１００ｎｍ以下であれば、リチウム含有複合酸化物の表面に均一に付着されやすい。
As the solvent, a solvent containing water is preferable from the viewpoint of stability and reactivity of the compound containing a metal element, a mixed solvent of water and a water-soluble alcohol and / or polyol is more preferable, and water is particularly preferable. Examples of the water-soluble alcohol include methanol, ethanol, 1-propanol, and 2-propanol. Examples of the polyol include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, polyethylene glycol, butanediol, and glycerin. The total content of the water-soluble alcohol and the polyol contained in the solvent is preferably 0 to 20% by mass, more preferably 0 to 10% by mass with respect to the total amount of each solvent (total amount of solvent). When the solvent is only water, it is particularly preferable because it is excellent in terms of safety, environment, handling, and cost.
The dynamic light scattering diameter of the oxide (I) fine particles contained in the composition (1) is preferably 1 to 100 nm, more preferably 2 to 50 nm, and particularly preferably 3 to 30 nm. The dynamic light scattering diameter is a median diameter of particles measured by a dynamic light scattering method, and is measured in a state where oxide (I) fine particles are dispersed in a solvent (for example, Nanotrack UPA manufactured by Nikkiso Co., Ltd.). Used). When the particle diameter is 1 nm or more, there are few impurities and a stable dispersion can be easily obtained. If the particle diameter is 100 nm or less, it is easy to adhere uniformly to the surface of the lithium-containing composite oxide.
さらに組成物（１）にはｐＨ調整剤が含まれていても良い。ｐＨ調整剤としては、加熱時に揮発または分解するものが好ましい。具体的には、酢酸、クエン酸、乳酸、ギ酸等の有機酸やアンモニアが好ましい。
組成物（１）のｐＨとしては、３〜１２が好ましく、３．５〜１２がより好ましく、４〜１０が特に好ましい。ｐＨが上記の範囲にあれば、リチウム含有複合酸化物と組成物（１）とを接触させたときのリチウム含有複合酸化物からのＬｉ元素の溶出が少なく、また、ｐＨ調整剤等の不純物が少ないため良好な電池特性が得られやすい。
Further, the composition (1) may contain a pH adjusting agent. As the pH adjuster, those that volatilize or decompose upon heating are preferable. Specifically, organic acids such as acetic acid, citric acid, lactic acid, and formic acid, and ammonia are preferable.
As pH of composition (1), 3-12 are preferable, 3.5-12 are more preferable, and 4-10 are especially preferable. When the pH is in the above range, there is little elution of Li element from the lithium-containing composite oxide when the lithium-containing composite oxide is brought into contact with the composition (1), and impurities such as a pH adjuster are present. Since there are few, it is easy to obtain favorable battery characteristics.
組成物（１）を調製する時には、必要に応じて分散処理を行うことが望ましい。分散処理方法としては、ボールミル、ビーズミル、高圧ホモジナイザー、高速ホモジナイザー、超音波分散装置等の公知の手法を用いることができる。分散処理によって、酸化物（Ｉ）の微粒子の溶媒への分散が容易に進み、安定して分散することができる。
酸化物（Ｉ）の微粒子の溶媒への分散性を向上させるために、組成物（１）は高分子分散剤や界面活性剤を含んでいても良い。ただし、高分子分散剤や界面活性剤が正極材に残留すると電池特性に悪影響を及ぼすため、組成物（１）中の高分子分散剤と界面活性剤の合計含有量は、酸化物（Ｉ）の微粒子に対して３質量％以下であることが望ましい。１質量％以下であればより好ましく、０〜０．１質量％であれば特に好ましい。
When preparing the composition (1), it is desirable to perform a dispersion treatment as necessary. As a dispersion treatment method, a known method such as a ball mill, a bead mill, a high-pressure homogenizer, a high-speed homogenizer, or an ultrasonic dispersion apparatus can be used. By the dispersion treatment, the dispersion of the oxide (I) fine particles in the solvent can easily proceed and can be stably dispersed.
In order to improve the dispersibility of the oxide (I) fine particles in the solvent, the composition (1) may contain a polymer dispersant or a surfactant. However, if the polymer dispersant or the surfactant remains in the positive electrode material, the battery characteristics are adversely affected. Therefore, the total content of the polymer dispersant and the surfactant in the composition (1) is the oxide (I). It is desirable that it is 3 mass% or less with respect to the fine particles. If it is 1 mass% or less, it is more preferable, and if it is 0-0.1 mass%, it is especially preferable.
本発明で使用される組成物（１）中に含まれる酸化物（Ｉ）の微粒子の濃度は、後の工程で加熱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、濃度が高すぎると粘度が高くなり、正極活物質を形成する他の元素源と組成物（１）との均一混合性が低下し、組成物（１）中に含まれる酸化物（Ｉ）の微粒子の濃度は金属元素の酸化物（Ｉ）の微粒子換算で０．５〜３０質量％が好ましく、４〜２０質量％が特に好ましい。 The concentration of the fine particles of the oxide (I) contained in the composition (1) used in the present invention is preferably higher because it is necessary to remove the solvent by heating in a subsequent step. However, if the concentration is too high, the viscosity increases, and the uniform mixing property of the composition (1) with another element source that forms the positive electrode active material decreases, and the oxide (I) contained in the composition (1) ) Is preferably 0.5 to 30% by mass, particularly preferably 4 to 20% by mass in terms of fine particles of the metal element oxide (I).
リチウム含有複合酸化物と組成物（１）との接触方法として、例えば、スプレーコート法、湿式方法を適用でき、スプレーコート法により組成物（１）をリチウム含有複合酸化物に噴霧する方法が特に好ましい。湿式方法では接触後にろ過または蒸発により溶媒を除去する必要があるためプロセスが煩雑になる。スプレーコート法の場合はプロセスが簡便であり、かつ酸化物（Ｉ）の微粒子をリチウム含有複合酸化物の表面に均一に付着させることができる。 As a contact method between the lithium-containing composite oxide and the composition (1), for example, a spray coating method or a wet method can be applied, and a method of spraying the composition (1) onto the lithium-containing composite oxide by the spray coating method is particularly preferable. preferable. In the wet method, since the solvent needs to be removed by filtration or evaporation after contact, the process becomes complicated. In the case of the spray coating method, the process is simple, and fine particles of the oxide (I) can be uniformly attached to the surface of the lithium-containing composite oxide.
リチウム含有複合酸化物に接触させる組成物（１）の量は、リチウム含有複合酸化物に対して１〜５０質量％が好ましく、２〜４０質量％がより好ましく、３〜３０質量％が特に好ましい。組成物（１）の割合が上記の範囲であればリチウム含有複合酸化物の表面に酸化物（Ｉ）の微粒子を均一に付着させやすく、かつリチウム含有複合酸化物に組成物（１）をスプレーコートする際にリチウム含有複合酸化物が塊にならず撹拌しやすい。 The amount of the composition (1) to be brought into contact with the lithium-containing composite oxide is preferably 1 to 50% by mass, more preferably 2 to 40% by mass, and particularly preferably 3 to 30% by mass with respect to the lithium-containing composite oxide. . If the proportion of the composition (1) is in the above range, the fine particles of the oxide (I) can be uniformly adhered to the surface of the lithium-containing composite oxide, and the composition (1) is sprayed onto the lithium-containing composite oxide. When coating, the lithium-containing composite oxide is not agglomerated and easy to stir.
さらに、本発明の製造方法においては、撹拌しているリチウム含有複合酸化物に組成物（１）を添加して、リチウム含有複合酸化物と組成物（１）とを混合することにより、組成物（１）をリチウム含有複合酸化物に接触させることが好ましい。撹拌装置としては、ドラムミキサーまたはソリッドエアーの低剪断力の撹拌機を用いることができる。撹拌混合しながら組成物（１）とリチウム含有複合酸化物を接触させることで、より均一に酸化物（Ｉ）の微粒子がリチウム含有複合酸化物の表面に付着した粒子（ＩＩ）を得ることができる。 Furthermore, in the production method of the present invention, the composition (1) is added to the stirred lithium-containing composite oxide, and the lithium-containing composite oxide and the composition (1) are mixed, thereby forming the composition. It is preferable to contact (1) with the lithium-containing composite oxide. As the stirring device, a drum mixer or a solid-air low shear stirring device can be used. By contacting the composition (1) and the lithium-containing composite oxide while stirring and mixing, particles (II) in which the fine particles of the oxide (I) adhere more uniformly to the surface of the lithium-containing composite oxide can be obtained. it can.
本発明のリチウムイオン二次電池用正極活物質の製造方法においては、リチウム含有複合酸化物と、組成物（１）とを接触させて、加熱する。リチウム含有複合酸化物と、組成物（１）とを接触させて、加熱することで、リチウム含有複合酸化物の表面に、上記酸化物（Ｉ）の微粒子を付着させることができ、かつ、水や有機成分等の揮発性の不純物が除去できる。 In the manufacturing method of the positive electrode active material for lithium ion secondary batteries of this invention, a lithium containing complex oxide and a composition (1) are made to contact and it heats. By contacting and heating the lithium-containing composite oxide and the composition (1), the fine particles of the oxide (I) can be attached to the surface of the lithium-containing composite oxide, and water And volatile impurities such as organic components can be removed.
加熱は、酸素含有雰囲気下で行うことが好ましい。加熱温度は、５０〜３５０℃であることが好ましく、１００〜３００℃がより好ましい。加熱温度が５０℃以上であれば、リチウム含有複合酸化物の表面に、上記酸化物（Ｉ）の微粒子を付着させることができ、さらに残留水分等の揮発性の不純物が少なくなってサイクル特性に悪影響を与えない。加熱温度が上記の範囲であれば酸化物（Ｉ）の微粒子とリチウムやリチウム含有複合酸化物との反応が進みにくく、酸化物（Ｉ）の微粒子がリチウム含有複合酸化物の表面に付着するためサイクル特性が向上する。 Heating is preferably performed in an oxygen-containing atmosphere. The heating temperature is preferably 50 to 350 ° C, more preferably 100 to 300 ° C. When the heating temperature is 50 ° C. or higher, the fine particles of the oxide (I) can be attached to the surface of the lithium-containing composite oxide, and the volatile impurities such as residual moisture are reduced, resulting in cycle characteristics. Does not adversely affect. If the heating temperature is in the above range, the reaction between the oxide (I) fine particles and lithium or lithium-containing composite oxide is difficult to proceed, and the oxide (I) fine particles adhere to the surface of the lithium-containing composite oxide. Cycle characteristics are improved.
加熱時間は、０．１〜２４時間が好ましく、０．５〜１８時間がより好ましく、１〜１２時間が特に好ましい。 The heating time is preferably 0.1 to 24 hours, more preferably 0.5 to 18 hours, and particularly preferably 1 to 12 hours.
＜正極＞
本発明のリチウムイオン二次電池用正極は、上記の正極活物質、導電材およびバインダーを含む。
リチウムイオン二次電池用正極は、正極集電体上（正極表面）に、本発明の正極活物質を含有する正極活物質層が形成されてなる。リチウムイオン二次電池用正極は、例えば、本発明の正極活物質、導電材およびバインダーを、溶媒に溶解させるか、分散媒に分散させるか、又は溶媒と混練することによって、スラリー又は混錬物を調製し、調製したスラリー又は混錬物を正極集電板に塗布等により担持させることによって、製造することができる。
<Positive electrode>
The positive electrode for lithium ion secondary batteries of this invention contains said positive electrode active material, a electrically conductive material, and a binder.
The positive electrode for a lithium ion secondary battery is formed by forming a positive electrode active material layer containing the positive electrode active material of the present invention on a positive electrode current collector (positive electrode surface). The positive electrode for a lithium ion secondary battery is, for example, a slurry or kneaded product by dissolving the positive electrode active material, the conductive material and the binder of the present invention in a solvent, dispersing in a dispersion medium, or kneading with a solvent. And the prepared slurry or kneaded material is supported on the positive electrode current collector plate by coating or the like.
導電材としては、アセチレンブラック、黒鉛、ケッチェンブラック等のカーボンブラック等が挙げられる。
バインダーとしては、ポリフッ化ビニリデン、ポリテトラフルオロエチレン等のフッ素系樹脂、ポリエチレン、ポリプロピレン等のポリオレフィン、スチレン・ブタジエンゴム、イソプレンゴム、ブタジエンゴム等の不飽和結合を有する重合体およびその共重合体、アクリル酸共重合体、メタクリル酸共重合体等のアクリル酸系重合体およびその共重合体等が挙げられる。
Examples of the conductive material include carbon black such as acetylene black, graphite, and ketjen black.
As binders, fluorine-containing resins such as polyvinylidene fluoride and polytetrafluoroethylene, polyolefins such as polyethylene and polypropylene, polymers having unsaturated bonds such as styrene / butadiene rubber, isoprene rubber and butadiene rubber, and copolymers thereof, Examples thereof include acrylic acid-based polymers such as acrylic acid copolymers and methacrylic acid copolymers, and copolymers thereof.
＜リチウムイオン二次電池＞
本発明のリチウムイオン二次電池は、上記のリチウムイオン二次電池用正極、負極および非水電解質を含む。
負極は、負極集電体上に、負極活物質を含有する負極活物質層が形成されてなる。例えば、負極活物質を有機溶媒と混錬することによってスラリーを調製し、調製したスラリーを負極集電体に塗布、乾燥、プレスすることによって、製造することができる。
<Lithium ion secondary battery>
The lithium ion secondary battery of this invention contains said positive electrode for lithium ion secondary batteries, a negative electrode, and a nonaqueous electrolyte.
The negative electrode is formed by forming a negative electrode active material layer containing a negative electrode active material on a negative electrode current collector. For example, it can be produced by preparing a slurry by kneading a negative electrode active material with an organic solvent, and applying, drying, and pressing the prepared slurry to a negative electrode current collector.
負極集電板としては、例えば、ニッケル箔、銅箔等の金属箔を用いることができる。
負極活物質としては、リチウムイオンを吸蔵、放出可能な材料であればよく、例えば、リチウム金属、リチウム合金、リチウム化合物、炭素材料、周期表１４、１５族の金属を主体とする酸化物、炭素化合物、炭化ケイ素化合物、酸化ケイ素化合物、硫化チタンおよび炭化ホウ素化合物等を用いることができる。
As the negative electrode current collector plate, for example, a metal foil such as a nickel foil or a copper foil can be used.
The negative electrode active material may be any material that can occlude and release lithium ions. For example, lithium metal, lithium alloy, lithium compound, carbon material, periodic table 14 and group 15 metal oxides, carbon Compounds, silicon carbide compounds, silicon oxide compounds, titanium sulfide, boron carbide compounds, and the like can be used.
リチウム合金およびリチウム化合物としては、リチウムと、リチウムと合金あるいは化合物を形成可能な金属とにより構成されるリチウム合金およびリチウム化合物を用いることができる。
炭素材料としては、例えば、難黒鉛化性炭素、人造黒鉛、天然黒鉛、熱分解炭素類、ピッチコークス、ニードルコークス、石油コークス等のコークス類、グラファイト類、ガラス状炭素類、フェノール樹脂やフラン樹脂等を適当な温度で焼成し炭素化した有機高分子化合物焼成体、炭素繊維、活性炭、カーボンブラック類等を用いることができる。
周期表１４族の金属としては、例えば、ケイ素あるいはスズであり、最も好ましくはケイ素である。また、比較的低い電位でリチウムイオンを吸蔵、放出可能な材料であれば、例えば、酸化鉄、酸化ルテニウム、酸化モリブデン、酸化タングステン、酸化チタン、酸化スズ等の酸化物およびその他の窒化物等も同様に用いることができる。
As the lithium alloy and the lithium compound, lithium alloys and lithium compounds composed of lithium and a metal capable of forming an alloy or compound with lithium can be used.
Examples of the carbon material include non-graphitizable carbon, artificial graphite, natural graphite, pyrolytic carbon, pitch coke, needle coke, petroleum coke, and other cokes, graphite, glassy carbon, phenolic resin, and furan resin. An organic polymer compound fired body, carbon fiber, activated carbon, carbon black or the like obtained by firing and carbonizing the above at an appropriate temperature can be used.
The group 14 metal of the periodic table is, for example, silicon or tin, and most preferably silicon. In addition, materials that can occlude and release lithium ions at a relatively low potential include, for example, oxides such as iron oxide, ruthenium oxide, molybdenum oxide, tungsten oxide, titanium oxide, and tin oxide, and other nitrides. It can be used similarly.
非水電解質としては、非水溶媒に電解質塩を溶解させた非水電解液を用いることが好ましい。
非水電解液としては、有機溶媒と電解質とを適宜組み合わせて調製されたものを用いることができる。有機溶媒としては、この種の電池に用いられるものであればいずれも使用可能であり、例えば、プロピレンカーボネート、エチレンカーボネート、ジエチルカーボネート、ジメチルカーボネート、１，２−ジメトキシエタン、１，２−ジエトキシエタン、γ−ブチロラクトン、ジエチルエーテル、スルホラン、メチルスルホラン、アセトニトリル、酢酸エステル、酪酸エステル、プロピオン酸エステル等を用いることができる。特に、電圧安定性の点からは、プロピレンカーボネート等の環状カーボネート類、ジメチルカーボネート、ジエチルカーボネート等の鎖状カーボネート類を使用することが好ましい。また、このような有機溶媒は、１種類を単独で用いてもよく、２種類以上を混合して用いてもよい。
As the nonaqueous electrolyte, it is preferable to use a nonaqueous electrolytic solution in which an electrolyte salt is dissolved in a nonaqueous solvent.
As the non-aqueous electrolyte, one prepared by appropriately combining an organic solvent and an electrolyte can be used. Any organic solvent can be used as long as it is used in this type of battery. For example, propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxy. Ethane, γ-butyrolactone, diethyl ether, sulfolane, methyl sulfolane, acetonitrile, acetic acid ester, butyric acid ester, propionic acid ester and the like can be used. In particular, from the viewpoint of voltage stability, it is preferable to use cyclic carbonates such as propylene carbonate and chain carbonates such as dimethyl carbonate and diethyl carbonate. Moreover, such an organic solvent may be used individually by 1 type, and 2 or more types may be mixed and used for it.
また、その他、非水電解質として、電解質塩を含有させた固体電解質、高分子電解質、高分子化合物等に電解質を混合または溶解させた固体状もしくはゲル状電解質等を用いることができる。
固体電解質としては、リチウムイオン伝導性を有する材料であればよく、例えば、無機固体電解質および高分子固体電解質のいずれをも用いることができる。
In addition, as the non-aqueous electrolyte, a solid electrolyte containing an electrolyte salt, a polymer electrolyte, a solid or gel electrolyte in which an electrolyte is mixed or dissolved, and the like can be used.
The solid electrolyte may be any material having lithium ion conductivity. For example, any of an inorganic solid electrolyte and a polymer solid electrolyte can be used.
無機固体電解質としては、窒化リチウム、ヨウ化リチウム等を用いることができる。
高分子固体電解質としては、電解質塩と該電解質塩を溶解する高分子化合物を用いることができる。そして、この高分子化合物としては、ポリ（エチレンオキサイド）や同架橋体等のエーテル系高分子、ポリ（メタクリレート）エステル系、アクリレート系等を、単独あるいは分子中に共重合または混合して用いることができる。
As the inorganic solid electrolyte, lithium nitride, lithium iodide, or the like can be used.
As the polymer solid electrolyte, an electrolyte salt and a polymer compound that dissolves the electrolyte salt can be used. As this polymer compound, an ether polymer such as poly (ethylene oxide) or a crosslinked product thereof, a poly (methacrylate) ester compound, an acrylate compound or the like may be used alone or copolymerized or mixed in the molecule. Can do.
ゲル状電解質のマトリックスとしては、上記の非水電解液を吸収してゲル化するものであればよく、種々の高分子を用いることができる。また、ゲル状電解質に用いられる高分子材料としては、例えば、ポリ（ビニリデンフルオロライド）、ポリ（ビニリデンフルオロライド−ｃｏ−ヘキサフルオロプロピレン）等のフッ素系高分子等を使用することができる。また、ゲル状電解質に用いられる高分子材料としては、例えば、ポリアクリロニトリルおよびポリアクリロニトリルの共重合体を使用することができる。また、ゲル状電解質に用いられる高分子材料としては、例えば、ポリエチレンオキサイドおよびポリエチレンオキサイドの共重合体、同架橋体等のエーテル系高分子を使用することができる。共重合モノマーとしては、例えば、ポリプロピレンオキサイド、メタクリル酸メチル、メタクリル酸ブチル、アクリル酸メチル、アクリル酸ブチル等を挙げることができる。
また、酸化還元反応に対する安定性の観点により、上記した高分子のうち、特にフッ素系高分子を用いることが好ましい。
The matrix of the gel electrolyte may be any matrix that absorbs the non-aqueous electrolyte and gels, and various polymers can be used. As the polymer material used for the gel electrolyte, for example, fluorine-based polymers such as poly (vinylidene fluoride) and poly (vinylidene fluoride-co-hexafluoropropylene) can be used. Moreover, as a polymer material used for the gel electrolyte, for example, polyacrylonitrile and a copolymer of polyacrylonitrile can be used. Moreover, as a polymer material used for the gel electrolyte, for example, an ether-based polymer such as polyethylene oxide, a polyethylene oxide copolymer, and a crosslinked product thereof can be used. Examples of the copolymerization monomer include polypropylene oxide, methyl methacrylate, butyl methacrylate, methyl acrylate, and butyl acrylate.
In addition, from the viewpoint of stability against the redox reaction, it is particularly preferable to use a fluorine-based polymer among the above-described polymers.
上記したような各種の電解質中で用いられる電解質塩は、この種の電池に用いられるものであればいずれも使用可能である。電解質塩としては、例えば、ＬｉＣｌＯ４、ＬｉＰＦ６、ＬｉＢＦ４、ＣＨ３ＳＯ３Ｌｉ、ＬｉＣｌ、ＬｉＢｒ等を用いることができる。
本発明のリチウムイオン二次電池の形状は、コイン型、シート状（フィルム状）、折り畳み状、巻回型有底円筒型、ボタン型等の形状を、用途に応じて適宜選択することができる。
Any electrolyte salt used in various electrolytes as described above can be used as long as it is used in this type of battery. As the electrolyte salt, for example, LiClO 4 , LiPF 6 , LiBF 4 , CH 3 SO 3 Li, LiCl, LiBr, or the like can be used.
The shape of the lithium ion secondary battery of the present invention can be appropriately selected from coin shapes, sheet shapes (film shapes), folded shapes, wound bottomed cylindrical shapes, button shapes, and the like according to applications. .
本発明のリチウムイオン二次電池用正極活物質は、初回充電（活性化）により不可逆的に変化して、主成分がＬｉＭＯ２であり、残部がＬｉ２ＭｎＯ３からなる組成になるものと推定される。主成分のＬｉＭＯ２は、Ｌｉ化合物とＭ化合物から直接合成したＬｉＭＯ２よりも放電時に脱離するＬｉ量が多いため、放電容量が高くなる。充放電反応は、下記式（３）で表される式に従い進行すると考えられる。
ＬｉＭＯ２→（充電）→Ｌｉ１−ｘＭＯ２+ｘＬｉ （３）
式（３）において、ｘＬｉは負極に吸蔵される。また、放電は、充電と逆の反応をする。前記正極活物質を構成する式（２）で表されるリチウム含有複合酸化物は、リチウムイオン二次電池を活性化する前の組成を表している。
The positive electrode active material for a lithium ion secondary battery of the present invention is irreversibly changed by initial charge (activation), and is assumed to have a composition in which the main component is LiMO 2 and the balance is Li 2 MnO 3. Is done. Since the main component LiMO 2 has a larger amount of Li desorbed at the time of discharge than LiMO 2 synthesized directly from the Li compound and the M compound, the discharge capacity is increased. The charge / discharge reaction is considered to proceed according to the formula represented by the following formula (3).
LiMO 2 → (charging) → Li 1-x MO 2 + xLi (3)
In Formula (3), xLi is occluded by the negative electrode. In addition, discharging has the opposite reaction to charging. The lithium-containing composite oxide represented by the formula (2) constituting the positive electrode active material represents a composition before the lithium ion secondary battery is activated.
＜リチウム含有複合酸化物の合成＞
硫酸ニッケル（ＩＩ）六水和物（１４０．６ｇ）、硫酸コバルト（ＩＩ）七水和物（１３１．４ｇ）、硫酸マンガン（ＩＩ）五水和物（４８２．２ｇ）に蒸留水（１２４５．９ｇ）を加えて均一に溶解させて原料溶液とした。硫酸アンモニウム（７９．２ｇ）に蒸留水（３２０．８ｇ）を加えて均一に溶解させてアンモニア源溶液とした。硫酸アンモニウム（７９．２ｇ）に蒸留水（１９２０．８ｇ）を加えて均一に溶解させて母液とした。水酸化ナトリウム（４００ｇ）に蒸留水（６００ｇ）を加えて均一に溶解させてｐＨ調整液とした。
<Synthesis of lithium-containing composite oxide>
Nickel (II) sulfate hexahydrate (140.6 g), cobalt sulfate (II) heptahydrate (131.4 g), manganese (II) sulfate pentahydrate (482.2 g) and distilled water (1245. 9 g) was added and dissolved uniformly to obtain a raw material solution. Distilled water (320.8 g) was added to ammonium sulfate (79.2 g) and dissolved uniformly to obtain an ammonia source solution. Distilled water (1920.8 g) was added to ammonium sulfate (79.2 g) and dissolved uniformly to obtain a mother liquor. Distilled water (600 g) was added to sodium hydroxide (400 g) and dissolved uniformly to obtain a pH adjusting solution.
２Ｌのバッフル付きガラス製反応槽に母液を入れてマントルヒーターで５０℃に加熱し、ｐＨが１１．０となるようにｐＨ調整液を加えた。反応槽内の溶液をアンカー型の撹拌翼で撹拌しながら原料溶液を５．０ｇ／分、アンモニア源溶液を１．０ｇ／分の速度で添加し、ニッケル、コバルト、マンガンの複合水酸化物を析出させた。原料溶液を添加している間、反応槽内のｐＨを１１．０に保つようにｐＨ調整溶液を添加した。また、析出した水酸化物が酸化しないように反応槽内に窒素ガスを流量０．５Ｌ／分で流した。また、反応槽内の液量が２Ｌを超えないように連続的に液の抜き出しを行った。 The mother liquor was placed in a 2 L baffled glass reaction vessel, heated to 50 ° C. with a mantle heater, and a pH adjusting solution was added so that the pH was 11.0. While stirring the solution in the reaction vessel with an anchor type stirring blade, the raw material solution was added at a rate of 5.0 g / min, and the ammonia source solution was added at a rate of 1.0 g / min, and a composite hydroxide of nickel, cobalt, and manganese was added. Precipitated. During the addition of the raw material solution, the pH adjusting solution was added so as to keep the pH in the reaction vessel at 11.0. Moreover, nitrogen gas was flowed at a flow rate of 0.5 L / min in the reaction tank so that the precipitated hydroxide was not oxidized. Further, the liquid was continuously extracted so that the amount of the liquid in the reaction tank did not exceed 2 L.
得られたニッケル、コバルト、マンガンの複合水酸化物から不純物イオンを取り除くため、加圧ろ過と蒸留水への分散を繰返して洗浄した。ろ液の電気伝導度が２５μＳ／ｃｍとなった時点で洗浄を終了し、１２０℃で１５時間乾燥させて前駆体とした。
ＩＣＰで前駆体のニッケル、コバルト、マンガンの含有量を測定したところ、それぞれ１１．６質量％、１０．５質量％、４２．３質量％であった（モル比でニッケル：コバルト：マンガン＝０．１７２：０．１５６：０．６７２）。
In order to remove impurity ions from the obtained composite hydroxide of nickel, cobalt, and manganese, washing was repeated by pressure filtration and dispersion in distilled water. When the electrical conductivity of the filtrate reached 25 μS / cm, the washing was finished and dried at 120 ° C. for 15 hours to obtain a precursor.
When the contents of the precursors nickel, cobalt, and manganese were measured by ICP, they were 11.6% by mass, 10.5% by mass, and 42.3% by mass, respectively (in terms of molar ratio, nickel: cobalt: manganese = 0). 172: 0.156: 0.672).
前駆体（２０ｇ）とリチウム含有量が２６．９ｍｏｌ／ｋｇの炭酸リチウム（１２．６ｇ）を混合して酸素含有雰囲気下８００℃で１２時間焼成し、実施例のリチウム含有複合酸化物を得た。得られた実施例のリチウム含有複合酸化物の組成はＬｉ（Ｌｉ０．２Ｎｉ０．１３７Ｃｏ０．１２５Ｍｎ０．５３８）Ｏ２となる。実施例のリチウム含有複合酸化物の平均粒子径Ｄ５０は５．３μｍであり、ＢＥＴ（Ｂｒｕｎａｕｅｒ，Ｅｍｍｅｔｔ，Ｔｅｌｌｅｒ）法を用いて測定した比表面積は４．４ｍ２／ｇであった。 A precursor (20 g) and lithium carbonate (12.6 g) having a lithium content of 26.9 mol / kg were mixed and baked at 800 ° C. for 12 hours in an oxygen-containing atmosphere to obtain a lithium-containing composite oxide of the example. . The composition of the lithium-containing composite oxide of the obtained example is Li (Li 0.2 Ni 0.137 Co 0.125 Mn 0.538 ) O 2 . The average particle diameter D50 of the lithium-containing composite oxide of the example was 5.3 μm, and the specific surface area measured using the BET (Brunauer, Emmett, Teller) method was 4.4 m 2 / g.
（実施例１）＜リチウム含有複合酸化物へのジルコニウム被覆＞
ジルコニウム含量がＺｒＯ２換算で３０質量％の酸性ジルコニア分散液（堺化学工業社製、ＳＺＲジルコニア水分散液）（０．７５ｇ）に、蒸留水（２４．２５ｇ）を加えて、ｐＨ３．９のＺｒＯ２分散液（組成物（１））を調製した。
次に、撹拌している実施例のリチウム含有複合酸化物（１５ｇ）に対して、調製したＺｒＯ２分散液（２．４ｇ）を噴霧して添加し、実施例のリチウム含有複合酸化物とＺｒＯ２分散液とを混合させながら接触させた。次いで、得られた混合物を、酸素含有雰囲気下３００℃で１時間加熱し、リチウム含有複合酸化物の表面にＺｒ元素の酸化物（Ｉ）の微粒子が付着する粒子（ＩＩ）からなる実施例１の正極活物質（Ａ）を得た。
(Example 1) <Zirconium coating on lithium-containing composite oxide>
Distilled water (24.25 g) was added to acidic zirconia dispersion (SZR zirconia aqueous dispersion manufactured by Sakai Chemical Industry Co., Ltd.) (0.75 g) having a zirconium content of 30% by mass in terms of ZrO 2 , and the pH was 3.9. A ZrO 2 dispersion (composition (1)) was prepared.
Next, the prepared ZrO 2 dispersion (2.4 g) was sprayed and added to the stirred lithium-containing composite oxide (15 g), and the lithium-containing composite oxide and ZrO of the example were added. The two dispersions were brought into contact with mixing. Next, the obtained mixture was heated at 300 ° C. for 1 hour in an oxygen-containing atmosphere, and Example 1 consisting of particles (II) in which fine particles of Zr element oxide (I) adhered to the surface of the lithium-containing composite oxide. The positive electrode active material (A) was obtained.
正極活物質（Ａ）に含まれる組成物（１）の金属元素（被覆材料）であるジルコニウムは、実施例のリチウム含有複合酸化物の遷移金属元素であるニッケル、コバルト、マンガンの合計に対して、モル比（被覆量）で｛（Ｚｒのモル数）/（Ｎｉ、Ｃｏ、Ｍｎの合計モル数）｝０．００１３であった。得られた正極活物質（Ａ）の粉末の断面を樹脂で包埋し、酸化セリウム微粒子で研磨し、正極活物質（Ａ）の粒子断面をＥＰＭＡ（Ｘ線マイクロアナライザ）でＺｒマッピングを行なった結果、粒子内部より、粒子外表面により多くのＺｒを検出できた。 Zirconium, which is the metal element (coating material) of the composition (1) contained in the positive electrode active material (A), is based on the total of nickel, cobalt, and manganese, which are transition metal elements of the lithium-containing composite oxide of the example. The molar ratio (coating amount) was {(number of moles of Zr) / (total number of moles of Ni, Co, and Mn)} 0.0013. A cross section of the obtained positive electrode active material (A) powder was embedded in resin and polished with fine cerium oxide particles, and the positive electrode active material (A) particle cross section was subjected to Zr mapping with EPMA (X-ray microanalyzer). As a result, more Zr could be detected on the outer surface of the particle than inside the particle.
（実施例２）＜リチウム含有複合酸化物へのジルコニウム被覆＞
ＺｒＯ２分散液（組成物（１））を調製する際に、酸性ジルコニア分散液（堺化学工業社製、ＳＺＲジルコニア水分散液）（３．７６ｇ）と蒸留水（２１．２４ｇ）を用いたこと以外は実施例１と同様にして、実施例２の正極活物質（Ｂ）を得た。
正極活物質（Ｂ）に含まれる組成物（１）の金属元素（被覆材料）であるジルコニウムは、実施例のリチウム含有複合酸化物の遷移金属元素であるニッケル、コバルト、マンガンの合計に対して、モル比（被覆量）で｛（Ｚｒのモル数）/（Ｎｉ、Ｃｏ、Ｍｎの合計モル数）｝０．００６３であった。
(Example 2) <Zirconium coating on lithium-containing composite oxide>
When preparing the ZrO 2 dispersion (composition (1)), an acidic zirconia dispersion (manufactured by Sakai Chemical Industry Co., Ltd., SZR zirconia aqueous dispersion) (3.76 g) and distilled water (21.24 g) were used. Except this, a positive electrode active material (B) of Example 2 was obtained in the same manner as Example 1.
Zirconium, which is the metal element (coating material) of the composition (1) contained in the positive electrode active material (B), is based on the total of nickel, cobalt, and manganese, which are transition metal elements of the lithium-containing composite oxide of the example. The molar ratio (coating amount) was {(number of moles of Zr) / (total number of moles of Ni, Co, Mn)} 0.0063.
（実施例３）＜リチウム含有複合酸化物へのジルコニウム被覆＞
ＺｒＯ２分散液（組成物（１））を調製する際に、酸性ジルコニア分散液（堺化学工業社製、ＳＺＲジルコニア水分散液）（１１．２８ｇ）と蒸留水（１３．７２ｇ）を用いたこと以外は実施例１と同様にして、実施例３の正極活物質（Ｃ）を得た。
正極活物質（Ｃ）に含まれる組成物（１）の金属元素（被覆材料）であるジルコニウムは、実施例のリチウム含有複合酸化物の遷移金属元素であるニッケル、コバルト、マンガンの合計に対して、モル比（被覆量）で｛（Ｚｒのモル数）/（Ｎｉ、Ｃｏ、Ｍｎの合計モル数）｝０．０１８９であった。
(Example 3) <Zirconium coating on lithium-containing composite oxide>
When preparing the ZrO 2 dispersion (composition (1)), an acidic zirconia dispersion (manufactured by Sakai Chemical Industry Co., Ltd., SZR zirconia aqueous dispersion) (11.28 g) and distilled water (13.72 g) were used. Except this, the positive electrode active material (C) of Example 3 was obtained in the same manner as Example 1.
Zirconium, which is a metal element (coating material) of the composition (1) contained in the positive electrode active material (C), is based on the total of nickel, cobalt, and manganese, which are transition metal elements of the lithium-containing composite oxide of the example. The molar ratio (coating amount) was {(number of moles of Zr) / (total number of moles of Ni, Co, Mn)} 0.0189.
（実施例４）＜リチウム含有複合酸化物へのジルコニウム被覆＞
ＺｒＯ２分散液（組成物（１））を調製する際に、酸性ジルコニア分散液（堺化学工業社製、ＳＺＲジルコニア水分散液）（２２．５５ｇ）と蒸留水（２．４５ｇ）を用い、ＺｒＯ２分散液の噴霧量を４．８ｇとしたこと以外は実施例１と同様にして、実施例４の正極活物質（Ｄ）を得た。
正極活物質（Ｄ）に含まれる組成物（１）の金属元素（被覆材料）であるジルコニウムは、実施例のリチウム含有複合酸化物の遷移金属元素であるニッケル、コバルト、マンガンの合計に対して、モル比（被覆量）で｛（Ｚｒのモル数）/（Ｎｉ、Ｃｏ、Ｍｎの合計モル数）｝０．０６３であった。
(Example 4) <Zirconium coating on lithium-containing composite oxide>
When preparing the ZrO 2 dispersion (composition (1)), an acidic zirconia dispersion (manufactured by Sakai Chemical Industry Co., Ltd., SZR zirconia aqueous dispersion) (22.55 g) and distilled water (2.45 g) were used. A positive electrode active material (D) of Example 4 was obtained in the same manner as in Example 1 except that the spray amount of the ZrO 2 dispersion was 4.8 g.
Zirconium, which is a metal element (coating material) of the composition (1) contained in the positive electrode active material (D), is based on the total of nickel, cobalt, and manganese, which are transition metal elements of the lithium-containing composite oxide of the example. The molar ratio (coating amount) was {(molar number of Zr) / (total molar number of Ni, Co, Mn)} 0.063.
（実施例５）＜リチウム含有複合酸化物へのジルコニウム被覆＞
ジルコニウム含量がＺｒＯ２換算で３０．８質量％の中性ジルコニア分散液（日産化学工業社製、ＺＲ−３０ＢＦジルコニア水分散液）（３．６６ｇ）に、蒸留水（２１．３４ｇ）を加えて、ｐＨ６．５のＺｒＯ２分散液（組成物（１））を調製し、実施例１と同様にして、実施例５の正極活物質（Ｅ）を得た。
正極活物質（Ｅ）に含まれる組成物（１）の金属元素（被覆材料）であるジルコニウムは、実施例のリチウム含有複合酸化物の遷移金属元素であるニッケル、コバルト、マンガンの合計に対して、モル比（被覆量）で｛（Ｚｒのモル数）/（Ｎｉ、Ｃｏ、Ｍｎの合計モル数）｝０．００６３であった。
(Example 5) <Zirconium coating on lithium-containing composite oxide>
Distilled water (21.34 g) was added to a neutral zirconia dispersion (ZR-30BF zirconia aqueous dispersion, manufactured by Nissan Chemical Industries, Ltd.) (3.66 g) having a zirconium content of 30.8% by mass in terms of ZrO 2. A ZrO 2 dispersion (composition (1)) having a pH of 6.5 was prepared, and a positive electrode active material (E) of Example 5 was obtained in the same manner as in Example 1.
Zirconium, which is the metal element (coating material) of the composition (1) contained in the positive electrode active material (E), is based on the total of nickel, cobalt, and manganese, which are transition metal elements of the lithium-containing composite oxide of the example. The molar ratio (coating amount) was {(number of moles of Zr) / (total number of moles of Ni, Co, Mn)} 0.0063.
（比較例１）＜被覆なし＞
実施例のリチウム含有複合酸化物に対して被覆処理は行わず、比較例１の正極活物質（Ｆ）とした。
(Comparative Example 1) <Without coating>
The lithium-containing composite oxide of the example was not subjected to coating treatment, and the positive electrode active material (F) of Comparative Example 1 was used.
（比較例２）
ジルコニア粉末（０．１０８ｇ）と、実施例のリチウム含有複合酸化物（１５ｇ）とを、乾燥状態で混合し、比較例２の正極活物質（Ｇ）とした。
正極活物質（Ｇ）に含まれる金属元素（被覆材料）であるジルコニウムは、実施例のリチウム含有複合酸化物の遷移金属元素であるニッケル、コバルト、マンガンの合計に対して、モル比（被覆量）で｛（Ｚｒのモル数）/（Ｎｉ、Ｃｏ、Ｍｎの合計モル数）｝０．００６３であった。
(Comparative Example 2)
Zirconia powder (0.108 g) and the lithium-containing composite oxide (15 g) of the example were mixed in a dry state to obtain a positive electrode active material (G) of Comparative Example 2.
Zirconium, which is a metal element (coating material) contained in the positive electrode active material (G), has a molar ratio (coating amount) with respect to the total of nickel, cobalt, and manganese, which are transition metal elements of the lithium-containing composite oxide of the example. ) {(Number of moles of Zr) / (total number of moles of Ni, Co, Mn)} 0.0063.
（比較例３）
ジルコニア粉末（１．０８ｇ）と、実施例のリチウム含有複合酸化物（１５ｇ）とを、乾燥状態で混合し、比較例２の正極活物質（Ｈ）とした。
正極活物質（Ｈ）に含まれる金属元素（被覆材料）であるジルコニウムは、実施例のリチウム含有複合酸化物の遷移金属元素であるニッケル、コバルト、マンガンの合計に対して、モル比（被覆量）で｛（Ｚｒのモル数）/（Ｎｉ、Ｃｏ、Ｍｎの合計モル数）｝０．０６３であった。
(Comparative Example 3)
Zirconia powder (1.08 g) and the lithium-containing composite oxide (15 g) of the example were mixed in a dry state to obtain a positive electrode active material (H) of Comparative Example 2.
Zirconium, which is a metal element (coating material) contained in the positive electrode active material (H), has a molar ratio (coating amount) with respect to the total of nickel, cobalt, and manganese, which are transition metal elements of the lithium-containing composite oxide of the example. ) {(Number of moles of Zr) / (total number of moles of Ni, Co, Mn)} 0.063.
＜正極体シートの作製＞
正極活物質として、実施例１〜実施例５、比較例１〜比較例３の正極活物質（Ａ）〜（Ｈ）をそれぞれ用い、正極活物質とアセチレンブラック（導電材）とポリフッ化ビニリデン（バインダー）を１２．１質量％含むポリフッ化ビニリデン溶液（溶媒Ｎ−メチルピロリドン）を混合し、さらにＮ−メチルピロリドンを添加してスラリーを作製した。正極活物質と、アセチレンブラックと、ポリフッ化ビニリデンは質量比で８０／１２／８とした。スラリーを厚さ２０μｍのアルミニウム箔（正極集電体）にドクターブレードを用いて片面塗工した。１２０℃で乾燥し、ロールプレス圧延を２回行うことによりリチウム電池用の正極となる実施例１〜実施例５、比較例１〜比較例３の正極体シートを作製した。
<Preparation of positive electrode sheet>
As the positive electrode active material, the positive electrode active materials (A) to (H) of Examples 1 to 5 and Comparative Examples 1 to 3 were used, respectively, and the positive electrode active material, acetylene black (conductive material), and polyvinylidene fluoride ( A polyvinylidene fluoride solution (solvent N-methylpyrrolidone) containing 12.1% by mass of a binder was mixed, and N-methylpyrrolidone was further added to prepare a slurry. The positive electrode active material, acetylene black, and polyvinylidene fluoride were in a mass ratio of 80/12/8. One side of the slurry was applied to a 20 μm thick aluminum foil (positive electrode current collector) using a doctor blade. It dried at 120 degreeC and produced the positive electrode body sheet | seat of Example 1- Example 5 used as the positive electrode for lithium batteries, and Comparative Example 1- Comparative Example 3 by performing roll press rolling twice.
＜電池の組み立て＞
前記の実施例１〜実施例５、比較例１〜比較例３の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、負極集電体に厚さ１ｍｍのステンレス板を使用し、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１（ｍｏｌ／ｄｍ３）のＬｉＰＦ６／ＥＣ（エチレンカーボネート）＋ＤＥＣ（ジエチルカーボネート）（１：１）溶液（ＬｉＰＦ６を溶質とするＥＣとＤＥＣとの体積比（ＥＣ：ＤＥＣ＝１：１）の混合溶液を意味する。）を用いてステンレス製簡易密閉セル型の実施例１〜実施例５、比較例１〜比較例３のリチウム電池をアルゴングローブボックス内で組み立てた。
<Battery assembly>
A punched positive electrode sheet of Examples 1 to 5 and Comparative Examples 1 to 3 is used for the positive electrode, a metal lithium foil having a thickness of 500 μm is used for the negative electrode, and the negative electrode current collector is 1 mm thick. The separator is made of 25 μm-thick porous polypropylene, and the electrolyte is LiPF 6 / EC (ethylene carbonate) + DEC (diethyl carbonate) (1) with a concentration of 1 (mol / dm 3 ). : 1) solution (volume ratio of the LiPF 6 EC and DEC to solute (EC: DEC = 1: 1). which means mixed solution) example 1 to the stainless steel simple closed cell type with The lithium batteries of Example 5 and Comparative Examples 1 to 3 were assembled in an argon glove box.
＜初期容量の評価＞＜サイクル特性の評価＞
前記実施例１〜実施例５、比較例１〜比較例３のリチウム電池について、２５℃にて電池評価を行った。
正極活物質１ｇにつき１５０ｍＡの負荷電流で４．８Ｖまで充電し、正極活物質１ｇにつき３７．５ｍＡの負荷電流にて２．５Ｖまで放電した。４．８〜２．５Ｖにおける正極活物質の放電容量を４．８Ｖ初期容量とする。続いて正極活物質１ｇにつき１５０ｍＡの負荷電流で４．３Ｖまで充電し、正極活物質１ｇにつき３７．５ｍＡの負荷電流にて２．５Ｖまで放電した。
<Evaluation of initial capacity><Evaluation of cycle characteristics>
The lithium batteries of Examples 1 to 5 and Comparative Examples 1 to 3 were evaluated at 25 ° C.
The positive electrode active material was charged to 4.8 V at a load current of 150 mA per 1 g of the positive electrode active material, and discharged to 2.5 V at a load current of 37.5 mA per 1 g of the positive electrode active material. The discharge capacity of the positive electrode active material at 4.8 to 2.5 V is set to 4.8 V initial capacity. Subsequently, the battery was charged to 4.3 V at a load current of 150 mA per 1 g of the positive electrode active material, and discharged to 2.5 V at a load current of 37.5 mA per 1 g of the positive electrode active material.
このような充放電を行った実施例１〜実施例５、比較例１〜比較例３のリチウム電池について引き続き充放電正極活物質１ｇにつき２００ｍＡの負荷電流で４．５Ｖまで充電し、正極活物質１ｇにつき１００ｍＡの負荷電流にて２．５Ｖまで放電する充放電サイクルを１００回繰返した。４．５Ｖ充放電サイクル１回目の放電容量を４．５Ｖ初期容量とする。４．５Ｖ充放電サイクル１００回目の放電容量を４．５Ｖ充放電サイクル１回目の放電容量で割った値をサイクル維持率とする。
実施例１〜実施例５、比較例１〜比較例３のリチウム電池について、４．８Ｖ初期容量、４．５Ｖ初期容量、５０サイクル目のサイクル維持率、１００サイクル目のサイクル維持率について表１にまとめる。
The lithium batteries of Examples 1 to 5 and Comparative Examples 1 to 3 that were charged and discharged in this manner were subsequently charged to 4.5 V at a load current of 200 mA per 1 g of the charge / discharge positive electrode active material, and the positive electrode active material A charge / discharge cycle of discharging to 2.5 V at a load current of 100 mA per 1 g was repeated 100 times. The first discharge capacity of the 4.5V charge / discharge cycle is set to the 4.5V initial capacity. A value obtained by dividing the discharge capacity at the 100th 4.5V charge / discharge cycle by the discharge capacity at the first 4.5V charge / discharge cycle is defined as a cycle maintenance ratio.
Table 1 shows the 4.8V initial capacity, 4.5V initial capacity, 50th cycle cycle retention rate, and 100th cycle cycle retention rate for the lithium batteries of Examples 1 to 5 and Comparative Examples 1 to 3. To summarize.
表１に示すように、実施例１〜実施例５のリチウム電池は、比較例１〜比較例３のリチウム電池と比較して、サイクル維持率が高かった。
また、実施例１〜実施例３では、正極活物質（Ａ）〜（Ｃ）に含まれるジルコニウムのモル比（被覆量）を上げると、サイクル維持率が向上した。また、正極活物質（Ｄ）に含まれるジルコニウムのモル比（被覆量）が０．０６３である実施例４は、前記モル比（被覆量）が０．０１８９である実施例３と比較して、サイクル維持率が低かった。また、正極活物質（Ｅ）に含まれるジルコニウムのモル比（被覆量）が０．００６３である実施例５は、前記モル比（被覆量）が０．００６３である実施例２と比較して、サイクル維持率が高かった。
As shown in Table 1, the lithium batteries of Examples 1 to 5 had a higher cycle retention rate than the lithium batteries of Comparative Examples 1 to 3.
In Examples 1 to 3, when the molar ratio (covering amount) of zirconium contained in the positive electrode active materials (A) to (C) was increased, the cycle retention ratio was improved. Further, Example 4 in which the molar ratio (coating amount) of zirconium contained in the positive electrode active material (D) is 0.063 is compared with Example 3 in which the molar ratio (coating amount) is 0.0189. The cycle maintenance rate was low. Further, Example 5 in which the molar ratio (covering amount) of zirconium contained in the positive electrode active material (E) is 0.0063 is compared with Example 2 in which the molar ratio (covering amount) is 0.0063. The cycle maintenance rate was high.
＜レート特性の評価＞
（実施例６）
４．５Ｖ初期容量の評価において、４．５Ｖから２．５Ｖまでの放電を正極活物質１ｇにつき１０００ｍＡの負荷電流で行った以外は実施例３の電池評価と同様に行った。
４．５Ｖ初期容量は１５２ｍＡｈ／ｇであり、実施例３の４．５Ｖ初期容量に対して７７％であった。
<Evaluation of rate characteristics>
(Example 6)
In the evaluation of the 4.5 V initial capacity, the same battery evaluation as in Example 3 was performed except that discharging from 4.5 V to 2.5 V was performed at a load current of 1000 mA per 1 g of the positive electrode active material.
The 4.5V initial capacity was 152 mAh / g, 77% of the 4.5V initial capacity of Example 3.
（比較例３）
４．５Ｖ初期容量の評価において、４．５Ｖから２．５Ｖまでの放電を正極活物質１ｇにつき１０００ｍＡの負荷電流で行った以外は比較例１の電池評価と同様に行った。
４．５Ｖ初期容量は９８ｍＡｈ／ｇであり、比較例１の４．５Ｖ初期容量に対して４７％であった。
(Comparative Example 3)
In the evaluation of the 4.5 V initial capacity, the battery evaluation of Comparative Example 1 was performed except that discharging from 4.5 V to 2.5 V was performed at a load current of 1000 mA per 1 g of the positive electrode active material.
The 4.5 V initial capacity was 98 mAh / g, 47% with respect to the 4.5 V initial capacity of Comparative Example 1.
本発明によれば、小型・軽量、単位質量あたりの放電容量が高く、かつサイクル特性、レート特性に優れるリチウムイオン二次電池用の正極活物質、正極およびリチウムイオン二次電池を得ることができ、携帯電話等の電子機器、車載用のバッテリー等に利用することができる。
According to the present invention, it is possible to obtain a positive electrode active material, a positive electrode, and a lithium ion secondary battery for a lithium ion secondary battery that are small and light, have a high discharge capacity per unit mass, and are excellent in cycle characteristics and rate characteristics. It can be used for electronic devices such as mobile phones, in-vehicle batteries, and the like.
Claims (13)
Ｌｉ（ＬｉｘＭｎｙＭｅｚ）ＯｐＦｑ （２）
（但し、式（２）において、Ｍｅは、Ｃｏ、Ｎｉ、Ｃｒ、Ｆｅ、Ａｌ、Ｔｉ、Ｚｒ、Ｍｇから選ばれる少なくとも一種の元素であり、０．０９＜ｘ＜０．３、０．４≦ｙ／（ｙ＋ｚ）≦０．８、ｘ＋ｙ＋ｚ＝１、１．９＜ｐ＜２．１、０≦ｑ≦０．１である。） The positive electrode active material according to claim 1, wherein the lithium-containing composite oxide is a compound represented by the following formula (2).
Li (Li x Mn y Me z ) O p F q (2)
(In the formula (2), Me is at least one element selected from Co, Ni, Cr, Fe, Al, Ti, Zr, and Mg, and 0.09 <x <0.3, 0.4 ≦ y / (y + z) ≦ 0.8, x + y + z = 1, 1.9 <p <2.1, 0 ≦ q ≦ 0.1.
組成物（１）：Ｚｒ、Ｔｉ、Ｓｎ、Ｍｇ、Ｂａ、Ｐｂ、Ｂｉ、Ｎｂ、Ｔａ、Ｚｎ、Ｙ、Ｌａ、Ｓｒ、Ｃｅ、ＩｎおよびＡｌから選ばれる少なくとも一種の金属元素の酸化物（Ｉ）の微粒子を溶媒に分散させた分散液。 Li element and at least one transition metal element selected from Ni, Co and Mn are included (however, the molar amount of Li element is more than 1.2 times the total molar amount of the transition metal element). By contacting and heating the lithium-containing composite oxide and the following composition (1), the surface of the lithium-containing composite oxide is coated with Zr, Ti, Sn, Mg, Ba, Pb, Bi, Nb, Ta. A positive electrode active material for a lithium ion secondary battery comprising particles (II) to which fine particles of oxide (I) of at least one metal element selected from Zn, Y, La, Sr, Ce, In and Al are attached is obtained. The manufacturing method of the positive electrode active material for lithium ion secondary batteries characterized by the above-mentioned.
Composition (1): oxide of at least one metal element selected from Zr, Ti, Sn, Mg, Ba, Pb, Bi, Nb, Ta, Zn, Y, La, Sr, Ce, In and Al (I ) In a solvent.
The contact between the lithium-containing composite oxide and the composition (1) is performed by spraying the composition onto the lithium-containing composite oxide by a spray coating method. The manufacturing method as described in.
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