JP2005276474A - Manufacturing method of positive active material for lithium battery, positive active material for lithium battery, electrode for lithium battery, and lithium battery - Google Patents

Manufacturing method of positive active material for lithium battery, positive active material for lithium battery, electrode for lithium battery, and lithium battery Download PDF

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JP2005276474A
JP2005276474A JP2004084554A JP2004084554A JP2005276474A JP 2005276474 A JP2005276474 A JP 2005276474A JP 2004084554 A JP2004084554 A JP 2004084554A JP 2004084554 A JP2004084554 A JP 2004084554A JP 2005276474 A JP2005276474 A JP 2005276474A
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lithium battery
active material
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lithium
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JP4401833B2 (en
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Koji Ono
宏次 大野
Tetsuji Yamada
哲司 山田
Yoshiyuki Toge
喜之 峠
Mitsumasa Saito
光正 斉藤
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Sumitomo Osaka Cement Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a positive active material for a lithium battery realizing high discharge capacity and stable charge/discharge cycle characteristics, or the like, to provide the positive active material for the lithium battery, to provide an electrode for the lithium battery, and to provide the lithium battery. <P>SOLUTION: The manufacturing method of a positive active material for a lithium battery is a manufacturing method of a positive active material for a lithium battery of Li<SB>x</SB>A<SB>y</SB>D<SB>z</SB>PO<SB>4</SB>(A is one kind selected from Co, Ni, Mn, Fe, Cu, and Cr, D is one kind or two kinds or more selected from Mg, Ca, Fe, Ni, Co, Mn, Zn, Ge, Cu, Cr, Ti, Sr, Ba, Sc, Y, Al, Ga, In, Si, B, and rare earth elements, and different from A, and 0≤x<2, 0<y<1.5, 0≤z<1.5) and is manufactured by adding a Li component, a P component, an A component, a D component, and an organic acid soluble in water to a solvent mainly comprising water, and heating the solution under a pressurized condition. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、リチウム電池用正極活物質の製造方法とリチウム電池用正極活物質及びリチウム電池用電極並びにリチウム電池に関し、更に詳しくは、高結晶性かつ微粒子のオリビン構造を有するリチウム金属リン酸塩を得ることができる技術に関するものである。   The present invention relates to a method for producing a positive electrode active material for a lithium battery, a positive electrode active material for a lithium battery, an electrode for a lithium battery, and a lithium battery, and more specifically, a lithium metal phosphate having a highly crystalline and fine olivine structure. It relates to the technology that can be obtained.

近年、携帯用電子機器やハイブリット自動車等に用いるための電池として二次電池の開発が進められている。
代表的な二次電池としては鉛蓄電池、アルカリ蓄電池、リチウム電池等が知られているが、特に、リチウム電池は、小型化、軽量化、高容量化が可能であり、しかも、高出力、高エネルギー密度を有していることから、大いに期待されている。
このリチウム電池は、リチウムイオンを可逆的に脱挿入可能な活物質を有する正極と、負極と、非水系の電解質から構成されている。 In recent years, secondary batteries have been developed as batteries for use in portable electronic devices, hybrid automobiles, and the like.
As typical secondary batteries, lead storage batteries, alkaline storage batteries, lithium batteries, and the like are known. In particular, lithium batteries can be reduced in size, weight, and capacity, and have high output and high capacity. It is highly expected because of its energy density.
This lithium battery is composed of a positive electrode having an active material capable of reversibly inserting and removing lithium ions, a negative electrode, and a non-aqueous electrolyte.

この正極自体は、正極活物質、導電助剤およびバインダーを含む電極材料により構成され、この電極材料を集電体と呼ばれる金属箔の表面に塗布することにより正極とされている。
この正極活物質としては、金属酸化物、金属硫化物、あるいはポリマー等が用いられ、例えば、硫化チタン（ＴｉＳ２）、硫化モリブデン（ＭｏＳ２）、セレン化ニオブ（ＮｂＳｅ２）、酸化バナジウム（Ｖ２Ｏ５）等のリチウム非含有化合物、あるいはＬｉＭＯ２（Ｍ＝Ｃｏ、Ｎｉ、Ｍｎ、Ｆｅ等）、ＬｉＭｎ２Ｏ４等のリチウム複合酸化物等が知られている。 The positive electrode itself is composed of an electrode material containing a positive electrode active material, a conductive additive, and a binder, and is formed into a positive electrode by applying this electrode material to the surface of a metal foil called a current collector.
As the positive electrode active material, a metal oxide, a metal sulfide, a polymer, or the like is used. For example, titanium sulfide (TiS 2 ), molybdenum sulfide (MoS 2 ), niobium selenide (NbSe 2 ), vanadium oxide (V Lithium-free compounds such as 2 O 5 ) or lithium composite oxides such as LiMO 2 (M = Co, Ni, Mn, Fe, etc.) and LiMn 2 O 4 are known.

従来、リチウム電池の正極活物質としては、高エネルギー密度で高電圧の電池を構成することが可能であることから、コバルト酸リチウム（ＬｉＣｏＯ２）が一般的に用いられてきた。
しかしながら、Ｃｏは地球上に偏在し、かつ希少な資源であるため、コストが高くつく他、安定供給が難しいという問題があり、そこで、Ｃｏに替わる資源として、地球上に豊富に存在し、しかも安価なＮｉやＭｎをベースにした正極活物質、例えば、ニッケル酸リチウム（ＬｉＮｉＯ２）、マンガン酸リチウム（ＬｉＭｎ２Ｏ４）等が用いられるようになった。 Conventionally, lithium cobalt oxide (LiCoO 2 ) has been generally used as a positive electrode active material for lithium batteries because it is possible to form a battery having a high energy density and a high voltage.
However, because Co is unevenly distributed on the earth and is a scarce resource, there are problems that it is costly and that it is difficult to stably supply, so there are abundant resources on the earth as an alternative to Co. A cheap positive electrode active material based on Ni or Mn, for example, lithium nickelate (LiNiO 2 ), lithium manganate (LiMn 2 O 4 ) or the like has come to be used.

しかしながら、ＬｉＮｉＯ２は、理論容量が大きく、かつ高放電電位を有するという長所があるものの、充放電サイクルが繰り返されることに伴ってＬｉＮｉＯ２の結晶構造が崩壊してしまい、その結果、放電容量が低下したり、熱安定性が劣化したり等の問題点が生じていた。
一方、ＬｉＭｎ２Ｏ４は、正スピネル型構造を有し、かつ空間群Ｆｄ3ｍを有することから、リチウム電極に対し４Ｖ級というＬｉＣｏＯ２と同等の高い電位を有し、しかも、合成が容易、高い電池容量等から非常に有望な材料であり、実用化もされていた。
このＬｉＭｎ２Ｏ４は、この様に優れた材料ではあるが、このＬｉＭｎ２Ｏ４を用いた電池では、高温保存時における容量劣化が大きく、Ｍｎが電解液に溶解してしまい、したがって、安定性やサイクル特性が充分でないという問題点が残されていた。 However, although LiNiO 2 has the advantages of a large theoretical capacity and a high discharge potential, the LiNiO 2 crystal structure collapses as the charge / discharge cycle is repeated, and as a result, the discharge capacity is reduced. There have been problems such as lowering and deterioration of thermal stability.
On the other hand, since LiMn 2 O 4 has a positive spinel structure and has a space group Fd 3 m, it has a high potential equivalent to 4 V class LiCoO 2 with respect to the lithium electrode, and is easy to synthesize. It is a very promising material from the viewpoint of battery capacity and has been put into practical use.
Although this LiMn 2 O 4 is such an excellent material, the battery using this LiMn 2 O 4 has a large capacity deterioration during high-temperature storage, and Mn is dissolved in the electrolytic solution. The problem remains that the properties and cycle characteristics are not sufficient.

そこで、オリビン構造を有するＦｅ、Ｍｎ、Ｃｏ、Ｎｉ等の遷移金属のリン酸化合物を正極活物質として用いたリチウム電池が提案され（特許文献１参照）、このオリビン構造を有する遷移金属のリン酸化合物として、資源的に豊富かつ安価な金属であるＦｅを用いたＬｉＦｅＰＯ４を正極活物質として用いたリチウム電池が提案されている（特許文献２参照）。
このＬｉＦｅＰＯ４は、金属リチウム（Ｌｉ）に対して３．３Ｖ程度の電位を示し、充放電可能な正極材料として用いることが可能である。
リチウム遷移金属リン酸塩の様なリン酸塩系物質は、従来より、いわゆる固相法が用いられている。
特開平９−１３４７２４号公報 特開平９−１７１８２７号公報 Accordingly, a lithium battery using a transition metal phosphate compound such as Fe, Mn, Co, or Ni having an olivine structure as a positive electrode active material has been proposed (see Patent Document 1), and a transition metal phosphate having this olivine structure. As a compound, a lithium battery using LiFePO 4 using Fe, which is a resource-rich and inexpensive metal, as a positive electrode active material has been proposed (see Patent Document 2).
This LiFePO 4 exhibits a potential of about 3.3 V with respect to metallic lithium (Li), and can be used as a chargeable / dischargeable positive electrode material.
Conventionally, a so-called solid phase method has been used for a phosphate-based material such as a lithium transition metal phosphate.
JP-A-9-134724 Japanese Patent Laid-Open No. 9-171827

しかしながら、従来のリチウム遷移金属リン酸塩の様なリチウム金属リン酸化合物は、固相法により合成されているために、不活性ガス雰囲気下での焼成と粉砕を繰り返す必要があり、複雑な操作が必要になるという問題点があった。
また、固相法では、粒子径を小さくするには、より低温かつ短時間で焼成するのがよいのであるが、この場合、合成時の焼成温度が低いために合成時の結晶化度や粒径を制御することが難しく、得られるリチウム金属リン酸化合物は小さな結晶子が無秩序に並んだ構造を有するものとなる。したがって、リチウム金属リン酸化合物の結晶相は十分に生成・発達せず、結晶性も低いものとなり、粒子内のイオンの拡散性や電子伝導性が悪く、充放電時の分極が大きくなるという問題点があった。 However, since lithium metal phosphate compounds such as conventional lithium transition metal phosphates are synthesized by the solid-phase method, it is necessary to repeat firing and pulverization in an inert gas atmosphere, which is a complicated operation. There was a problem that it was necessary.
In the solid phase method, in order to reduce the particle size, it is better to fire at a lower temperature and in a shorter time. In this case, since the firing temperature at the time of synthesis is low, the crystallinity and grain size at the time of synthesis are reduced. It is difficult to control the diameter, and the obtained lithium metal phosphate compound has a structure in which small crystallites are arranged randomly. Therefore, the crystal phase of the lithium metal phosphate compound is not sufficiently generated / developed, the crystallinity is low, the diffusibility of ions in the particles and the electron conductivity are poor, and the polarization during charge / discharge increases. There was a point.

また、粒子径を小さくする方法として焼成後に粉砕する方法もあるが、この方法では、十分小さな粒子径にまで粉砕することができず、また、粉砕中に粒子自体に過度の力が掛かるために、歪や割れが生じ、結晶性も低下する。したがって、この方法で得られたリチウム金属リン酸化合物をリチウム電池に用いた場合、充放電によるリチウムイオンの挿入脱離に伴い、活物質の体積変化が起こり、これが繰り返されることで粒子に亀裂が入り、さらに亀裂が進行して粒子が破壊され、微細化されることとなり、その結果、粒子内のイオン拡散性及び粒子間のインピーダンスが増加し、放電時の分極が大きくなるという問題点があった。   In addition, there is a method of pulverizing after firing as a method of reducing the particle size, but this method cannot pulverize to a sufficiently small particle size, and excessive force is applied to the particles themselves during pulverization. , Distortion and cracking occur, and crystallinity also decreases. Therefore, when the lithium metal phosphate compound obtained by this method is used in a lithium battery, the volume change of the active material occurs with the insertion / extraction of lithium ions due to charge / discharge, and the particles are cracked by repeating this. Then, cracks progress and the particles are destroyed and refined. As a result, the ion diffusibility in the particles and the impedance between the particles increase, and the polarization during discharge increases. It was.

そこで、リチウム遷移金属リン酸塩の様なリチウム金属リン酸化合物に、比較的低温で結晶性の高い材料を合成することのできる水熱法を適用することも試みられているが、しかしながら、水熱法をリチウム金属リン酸化合物に適用した場合、原料混合時に溶解度の低いＬｉ３ＰＯ４やＦｅ３（ＰＯ４）２ が生じ、リチウム金属リン酸化合物の純度が低下してしまうという問題点があった。そこで、Ｌｉ３ＰＯ４やＦｅ３（ＰＯ４）２ を完全に反応させるためには、反応温度を高めたり、反応時間を延長したり等が必要になるが、その場合、粒子が粗大化し易くなり、微粒子化が困難になる等、必ずしも水熱法の利点が得られないという問題点があった。
このリチウム金属リン酸化合物の純度の低下や粒子の粗大化は、充放電時の電流密度を低下させ、その結果、高出力化を妨げる要因になる。 Therefore, it has been attempted to apply a hydrothermal method capable of synthesizing a material having high crystallinity at a relatively low temperature to a lithium metal phosphate compound such as a lithium transition metal phosphate. When the thermal method is applied to a lithium metal phosphate compound, Li 3 PO 4 and Fe 3 (PO 4 ) 2 having low solubility are generated when the raw materials are mixed, and the purity of the lithium metal phosphate compound is lowered. there were. Therefore, in order to completely react Li 3 PO 4 and Fe 3 (PO 4 ) 2 , it is necessary to increase the reaction temperature, extend the reaction time, etc. In this case, the particles are likely to be coarsened. Thus, there is a problem that the advantages of the hydrothermal method cannot always be obtained, such as difficulty in making fine particles.
This decrease in the purity of the lithium metal phosphate compound and the coarsening of the particles decrease the current density during charge and discharge, and as a result, hinder the increase in output.

本発明は、上記の課題を解決するためになされたものであって、安価で資源的に豊富な元素を用い、高い放電容量、安定した充放電サイクル特性、高い充填性及び高い出力を実現することができるリチウム電池用正極活物質の製造方法とリチウム電池用正極活物質及びリチウム電池用電極並びにリチウム電池を提供することを目的とする。   The present invention has been made in order to solve the above-described problems, and realizes high discharge capacity, stable charge / discharge cycle characteristics, high fillability, and high output by using inexpensive and resource-rich elements. It is an object to provide a method for producing a positive electrode active material for a lithium battery, a positive electrode active material for a lithium battery, an electrode for a lithium battery, and a lithium battery.

本発明者等は、鋭意検討を行った結果、リチウム金属リン酸化合物（ＬｉｘＡｙＤｚＰＯ４）は、従来用いられているＬｉＣｏＯ２等の電極材料に比べて電子導電性が低く、この点が、充放電時の電流密度が低く、高出力化が困難である原因の一つであると考え、そこで、より多くの電流を流すためには、材料の比表面積を大きくすること、すなわち微粒子化することが有効であると考え、水熱法によりリチウム金属リン酸化合物（ＬｉｘＡｙＤｚＰＯ４）を合成する際に、反応系内にクエン酸の様な高温で分解する水可溶性有機酸を添加すれば、原料を含む溶液を均一化することができ、高結晶性かつ微粒子のリチウム金属リン酸化合物（ＬｉｘＡｙＤｚＰＯ４）が得られることを見出し、本発明を完成するに至った。 As a result of intensive studies, the present inventors have found that the lithium metal phosphate compound (Li x A y D z PO 4 ) has a low electronic conductivity compared to a conventionally used electrode material such as LiCoO 2 , This point is considered to be one of the causes that current density at the time of charge and discharge is low and high output is difficult, so in order to flow more current, increase the specific surface area of the material, That is, it is considered effective to make fine particles, and when a lithium metal phosphate compound (Li x A y D z PO 4 ) is synthesized by a hydrothermal method, the reaction system decomposes at a high temperature such as citric acid. It has been found that if a water-soluble organic acid is added, the solution containing the raw material can be homogenized, and a highly crystalline and fine lithium metal phosphate compound (Li x A y D z PO 4 ) can be obtained. The invention has been completed.

すなわち、本発明のリチウム電池用正極活物質の製造方法は、ＬｉｘＡｙＤｚＰＯ４（但し、ＡはＣｏ、Ｎｉ、Ｍｎ、Ｆｅ、Ｃｕ、Ｃｒから選択された１種、ＤはＭｇ、Ｃａ、Ｆｅ、Ｎｉ、Ｃｏ、Ｍｎ、Ｚｎ、Ｇｅ、Ｃｕ、Ｃｒ、Ｔｉ、Ｓｒ、Ｂａ、Ｓｃ、Ｙ、Ａｌ、Ｇａ、Ｉｎ、Ｓｉ、Ｂ、希土類元素から選択された１種または２種以上かつ前記Ａと異なる、０≦ｘ＜２、０＜ｙ＜１．５、０≦ｚ＜１．５）にて表されるリチウム電池用正極活物質の製造方法であって、水を主成分とする溶媒に、リチウム（Ｌｉ）成分、リン（Ｐ）成分、前記Ａ成分、前記Ｄ成分及び水に可溶な有機酸を加え、次いで、この溶液を加圧下にて加熱することにより、前記ＬｉｘＡｙＤｚＰＯ４を生成することを特徴とする。 That is, the manufacturing method of the positive electrode active material for a lithium battery of the present invention is Li x A y D z PO 4 (where A is one selected from Co, Ni, Mn, Fe, Cu, Cr, and D is Mg , Ca, Fe, Ni, Co, Mn, Zn, Ge, Cu, Cr, Ti, Sr, Ba, Sc, Y, Al, Ga, In, Si, B, one or two selected from rare earth elements A method for producing a positive electrode active material for a lithium battery represented by 0 ≦ x <2, 0 <y <1.5, 0 ≦ z <1.5, which is different from the above-described A. By adding a lithium (Li) component, a phosphorus (P) component, the A component, the D component, and an organic acid soluble in water to a solvent as a component, and then heating the solution under pressure, The Li x A y D z PO 4 is generated.

このリチウム電池用正極活物質の製造方法では、ＬｉｘＡｙＤｚＰＯ４が微粒子化されることで、粒子表面の反応面積と、反応進行後の粒子内部での反応面積との差が小さくなり、より理論容量に近い状態まで充放電が可能となる。また、微粒子化されることで、粒子の表面積が大きくなり、反応界面における電流密度が低くなり、より大電流での充放電が可能となる。 In this method for producing a positive electrode active material for a lithium battery, the difference between the reaction area on the particle surface and the reaction area inside the particle after the reaction proceeds is small by making Li x A y D z PO 4 into fine particles. Thus, charging and discharging can be performed to a state closer to the theoretical capacity. Further, by making fine particles, the surface area of the particles is increased, the current density at the reaction interface is decreased, and charging / discharging with a larger current becomes possible.

前記有機酸は、ヒドロキシカルボン酸またはカルボン酸であることが好ましい。
前記ヒドロキシカルボン酸は、クエン酸、リンゴ酸、乳酸、酒石酸の群から選択された１種または２種以上であることが好ましい。
前記Ａは、Ｃｏ、Ｎｉ、Ｍｎ、Ｆｅから選択された１種であることが好ましい。
前記Ｄは、Ｍｇ、Ｃａ、Ｎｉ、Ｃｏ、Ｍｎ、Ｚｎ、Ｔｉ、Ａｌから選択された１種または２種以上であることが好ましい。 The organic acid is preferably a hydroxycarboxylic acid or a carboxylic acid.
The hydroxycarboxylic acid is preferably one or more selected from the group consisting of citric acid, malic acid, lactic acid, and tartaric acid.
The A is preferably one selected from Co, Ni, Mn, and Fe.
The D is preferably one or more selected from Mg, Ca, Ni, Co, Mn, Zn, Ti, and Al.

本発明のリチウム電池用正極活物質は、本発明のリチウム電池用正極活物質の製造方法により得られたことを特徴とする。   The positive electrode active material for a lithium battery of the present invention is obtained by the method for producing a positive electrode active material for a lithium battery of the present invention.

本発明のリチウム電池用電極は、本発明のリチウム電池用正極活物質を含有してなることを特徴とする。   The lithium battery electrode of the present invention is characterized by containing the positive electrode active material for a lithium battery of the present invention.

本発明のリチウム電池は、本発明のリチウム電池用電極を正電極として備えてなることを特徴とする。   The lithium battery of the present invention comprises the lithium battery electrode of the present invention as a positive electrode.

本発明のリチウム電池用正極活物質の製造方法によれば、ＬｉｘＡｙＤｚＰＯ４（但し、ＡはＣｏ、Ｎｉ、Ｍｎ、Ｆｅ、Ｃｕ、Ｃｒから選択された１種、ＤはＭｇ、Ｃａ、Ｆｅ、Ｎｉ、Ｃｏ、Ｍｎ、Ｚｎ、Ｇｅ、Ｃｕ、Ｃｒ、Ｔｉ、Ｓｒ、Ｂａ、Ｓｃ、Ｙ、Ａｌ、Ｇａ、Ｉｎ、Ｓｉ、Ｂ、希土類元素から選択された１種または２種以上かつ前記Ａと異なる、０≦ｘ＜２、０＜ｙ＜１．５、０≦ｚ＜１．５）にて表されるリチウム電池用正極活物質を製造する際に、水を主成分とする溶媒に、Ｌｉ成分、Ｐ成分、前記Ａ成分、前記Ｄ成分及び水に可溶な有機酸を加え、次いで、この溶液を加圧下にて加熱するので、Ｌｉ成分、Ｐ成分、Ａ成分及びＤ成分を含む水溶液を水に可溶な有機酸により均一化することができる。したがって、この水溶液から水熱法により微粒子を生成することで、高結晶性かつ微粒子のＬｉｘＡｙＤｚＰＯ４を作製することができる。 According to the method for producing a positive electrode active material for a lithium battery of the present invention, Li x A y D z PO 4 (where A is one selected from Co, Ni, Mn, Fe, Cu, Cr, and D is Mg , Ca, Fe, Ni, Co, Mn, Zn, Ge, Cu, Cr, Ti, Sr, Ba, Sc, Y, Al, Ga, In, Si, B, one or two selected from rare earth elements When producing a positive electrode active material for a lithium battery, which is different from A and represented by 0 ≦ x <2, 0 <y <1.5, 0 ≦ z <1.5), water is the main component. Li component, P component, A component, D component and water-soluble organic acid are added to the solvent, and then this solution is heated under pressure, so that Li component, P component, A component And the aqueous solution containing D component can be homogenized with the organic acid soluble in water. Therefore, by producing fine particles from this aqueous solution by a hydrothermal method, it is possible to produce highly crystalline and fine-particle Li x A y D z PO 4 .

本発明のリチウム電池用正極活物質によれば、本発明のリチウム電池用正極活物質の製造方法により得られたので、リチウム電池用正極活物質の主成分であるＬｉｘＡｙＤｚＰＯ４を高結晶化かつ微粒子化することができ、充放電容量を大幅に向上させることができ、安定した充放電サイクル特性を実現することができる。 According to the positive electrode active material for a lithium battery of the present invention, Li x A y D z PO 4 which is the main component of the positive electrode active material for a lithium battery is obtained by the method for producing a positive electrode active material for a lithium battery of the present invention. Can be highly crystallized and finely divided, the charge / discharge capacity can be greatly improved, and stable charge / discharge cycle characteristics can be realized.

本発明のリチウム電池用電極によれば、本発明のリチウム電池用正極活物質を含有したので、充放電容量を大幅に向上させることができ、安定した充放電サイクル特性を実現することができ、リチウム電池用電極の高品質化、小型化を図ることができる。   According to the electrode for lithium battery of the present invention, since the positive electrode active material for lithium battery of the present invention is contained, the charge / discharge capacity can be greatly improved, and stable charge / discharge cycle characteristics can be realized, The quality and size of the lithium battery electrode can be reduced.

本発明のリチウム電池によれば、本発明のリチウム電池用電極を正電極として備えたので、充放電容量を大幅に向上させることができ、安定した充放電サイクル特性を実現することができ、電池としての出力を高めることができる。したがって、各種電気特性に優れたリチウム電池を提供することができる。   According to the lithium battery of the present invention, since the lithium battery electrode of the present invention is provided as a positive electrode, the charge / discharge capacity can be greatly improved, and stable charge / discharge cycle characteristics can be realized. As an output can be increased. Therefore, it is possible to provide a lithium battery excellent in various electric characteristics.

本発明のリチウム電池用正極活物質の製造方法とリチウム電池用正極活物質及びリチウム電池用電極並びにリチウム電池の最良の形態について説明する。
なお、この形態は、発明の趣旨をより良く理解させるために具体的に説明するものであり、特に指定のない限り、本発明を限定するものではない。 The manufacturing method of the positive electrode active material for lithium batteries of this invention, the positive electrode active material for lithium batteries, the electrode for lithium batteries, and the best form of a lithium battery are demonstrated.
This embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

本発明のリチウム電池用正極活物質の製造方法は、ＬｉｘＡｙＤｚＰＯ４（但し、ＡはＣｏ、Ｎｉ、Ｍｎ、Ｆｅ、Ｃｕ、Ｃｒから選択された１種、ＤはＭｇ、Ｃａ、Ｆｅ、Ｎｉ、Ｃｏ、Ｍｎ、Ｚｎ、Ｇｅ、Ｃｕ、Ｃｒ、Ｔｉ、Ｓｒ、Ｂａ、Ｓｃ、Ｙ、Ａｌ、Ｇａ、Ｉｎ、Ｓｉ、Ｂ、希土類元素から選択された１種または２種以上かつ前記Ａと異なる、０≦ｘ＜２、０＜ｙ＜１．５、０≦ｚ＜１．５）にて表されるリチウム電池用正極活物質の製造方法であって、水を主成分とする溶媒に、Ｌｉ成分、Ｐ成分、前記Ａ成分、前記Ｄ成分及び水に可溶な有機酸を加え、次いで、この溶液を加圧下にて加熱することにより、前記ＬｉｘＡｙＤｚＰＯ４を生成する方法である。 The method for producing a positive electrode active material for a lithium battery of the present invention is Li x A y D z PO 4 (where A is one selected from Co, Ni, Mn, Fe, Cu, Cr, and D is Mg, Ca Fe, Ni, Co, Mn, Zn, Ge, Cu, Cr, Ti, Sr, Ba, Sc, Y, Al, Ga, In, Si, B, one or more selected from rare earth elements and A method for producing a positive electrode active material for a lithium battery, which is different from A and represented by 0 ≦ x <2, 0 <y <1.5, 0 ≦ z <1.5), wherein water is a main component. Li component, P component, A component, D component and water-soluble organic acid are added to the solvent to be heated, and then the solution is heated under pressure, whereby the Li x A y D z PO 4 is a method of generating 4 .

上記の有機酸としては、ヒドロキシカルボン酸またはカルボン酸が好ましく、ヒドロキシカルボン酸としては、クエン酸、リンゴ酸、乳酸、酒石酸の群から選択された１種または２種以上が好ましい。
Ａとしては、Ｃｏ、Ｎｉ、Ｍｎ、Ｆｅから選択された１種が好ましい。
Ｄとしては、Ｍｇ、Ｃａ、Ｎｉ、Ｃｏ、Ｍｎ、Ｚｎ、Ｔｉ、Ａｌから選択された１種または２種以上が好ましい。 The organic acid is preferably a hydroxycarboxylic acid or carboxylic acid, and the hydroxycarboxylic acid is preferably one or more selected from the group consisting of citric acid, malic acid, lactic acid, and tartaric acid.
A is preferably one selected from Co, Ni, Mn, and Fe.
D is preferably one or more selected from Mg, Ca, Ni, Co, Mn, Zn, Ti, and Al.

上記のＬｉｘＡｙＤｚＰＯ４を水熱法により生成する際に、リチウム（Ｌｉ）成分、リン（Ｐ）成分、Ａ成分及びＤ成分を、水を主成分とする溶媒に加えた場合、例えば、Ｌｉ３ＰＯ４やＦｅ３（ＰＯ４）２の様な難溶性物質が生じる。
これら難溶性物質は、耐圧容器内で加熱されることにより、温度が上昇するとともに溶解し、生じたＬｉ＋、Ｆｅ２＋、ＰＯ４ ３−等のイオンが反応することにより、ＬｉＦｅＰＯ４結晶核が生成、成長する。この際、Ｌｉ３ＰＯ４やＦｅ３（ＰＯ４）２を完全に溶解させるために温度を上げたり、加熱時間を延長したりすると、ＬｉＦｅＰＯ４結晶核が異常成長してしまう。 When Li x A y D z PO 4 is produced by the hydrothermal method, a lithium (Li) component, a phosphorus (P) component, an A component and a D component are added to a solvent containing water as a main component. For example, a hardly soluble substance such as Li 3 PO 4 or Fe 3 (PO 4 ) 2 is generated.
These hardly soluble substances are dissolved as the temperature rises when heated in a pressure-resistant vessel, and the generated Li + , Fe 2+ , PO 4 3−, and other ions react to form LiFePO 4 crystal nuclei. Generate and grow. At this time, if the temperature is increased or the heating time is extended to completely dissolve Li 3 PO 4 or Fe 3 (PO 4 ) 2 , LiFePO 4 crystal nuclei will grow abnormally.

本発明の製造方法では、Ｌｉ成分、Ｐ成分、Ａ成分及びＤ成分に、さらに、高温で分解するクエン酸の様な水に可溶な有機酸を加えることにより、難溶性物質が生成せず、原料を均一な溶液とすることができる。そして、この溶液を加圧下にて加熱することにより、有機酸の分解に伴って溶液全体から大きさが均一なＬｉｘＡｙＤｚＰＯ４結晶核を多数生じさせることができ、このＬｉｘＡｙＤｚＰＯ４結晶核を基に大きさが均一なＬｉｘＡｙＤｚＰＯ４微粒子を成長させることができる。
さらに、原料を溶液化することで、反応をより一層均一化することができ、高結晶性のＬｉｘＡｙＤｚＰＯ４微粒子を、より温和な条件下で合成することができ、しかも、ＬｉｘＡｙＤｚＰＯ４結晶核が異常成長するのを抑制することができる。 In the production method of the present invention, a hardly soluble substance is not generated by adding an organic acid soluble in water such as citric acid that decomposes at high temperature to the Li component, P component, A component, and D component. The raw material can be made into a uniform solution. Then, by heating this solution under pressure, a large number of Li x A y D z PO 4 crystal nuclei having a uniform size can be generated from the entire solution as the organic acid decomposes, and this Li x Li x A y D z PO 4 fine particles having a uniform size can be grown based on the A y D z PO 4 crystal nucleus.
Furthermore, by making the raw material into a solution, the reaction can be made more uniform, and highly crystalline Li x A y D z PO 4 fine particles can be synthesized under milder conditions, Abnormal growth of Li x A y D z PO 4 crystal nuclei can be suppressed.

次に、本発明のリチウム電池用正極活物質の製造方法について、より具体的に説明する。
まず、水を主成分とする溶媒に、Ｌｉ成分、Ｐ成分、Ａ成分（但し、ＡはＣｏ、Ｎｉ、Ｍｎ、Ｆｅ、Ｃｕ、Ｃｒから選択された１種）、Ｄ成分（但し、ＤはＭｇ、Ｃａ、Ｆｅ、Ｎｉ、Ｃｏ、Ｍｎ、Ｚｎ、Ｇｅ、Ｃｕ、Ｃｒ、Ｔｉ、Ｓｒ、Ｂａ、Ｓｃ、Ｙ、Ａｌ、Ｇａ、Ｉｎ、Ｓｉ、Ｂ、希土類元素から選択された１種または２種以上かつ前記Ａと異なる）を加え、出発原料を調整する。ここで、希土類元素とは、ランタン系列であるＬａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕの１５元素のことである。 Next, the manufacturing method of the positive electrode active material for lithium batteries of this invention is demonstrated more concretely.
First, in a solvent containing water as a main component, a Li component, a P component, and an A component (where A is one selected from Co, Ni, Mn, Fe, Cu, and Cr), a D component (where D is One or two selected from Mg, Ca, Fe, Ni, Co, Mn, Zn, Ge, Cu, Cr, Ti, Sr, Ba, Sc, Y, Al, Ga, In, Si, B, rare earth elements The starting material is prepared by adding more than seeds and different from A). Here, the rare earth elements are 15 elements of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu which are lanthanum series.

ここで、この出発原料に、さらに水に可溶な有機酸を加えることにより、難溶性物質を生成せずに溶液化された原料を調整することができる。
Ｌｉ成分としては、例えば、水酸化リチウム（ＬｉＯＨ）、炭酸リチウム（Ｌｉ２ＣＯ３）、リン酸リチウム(Ｌｉ３ＰＯ４）等のリチウム無機酸塩、酢酸リチウム（ＬｉＣＨ３ＣＯＯ）、蓚酸リチウム（（ＣＯＯＬｉ）２）等のリチウム有機酸塩が挙げられる。 Here, by adding an organic acid that is soluble in water to the starting material, it is possible to prepare a raw material in solution without producing a hardly soluble substance.
Examples of the Li component include lithium inorganic acid salts such as lithium hydroxide (LiOH), lithium carbonate (Li 2 CO 3 ), lithium phosphate (Li 3 PO 4 ), lithium acetate (LiCH 3 COO), lithium oxalate ( Examples include lithium organic acid salts such as (COOLi) 2 ).

リン成分としては、例えば、オルトリン酸（Ｈ３ＰＯ４）、メタリン酸（ＨＰＯ３）等のリン酸、リン酸水素２アンモニウム（（ＮＨ４）２ＨＰＯ４）、リン酸２水素アンモニウム（ＮＨ４Ｈ２ＰＯ４）等のリン酸水素アンモニウム等が挙げられ、比較的純度が高く組成制御が行い易いことから、オルトリン酸、リン酸水素２アンモニウム、リン酸２水素アンモニウムが好ましい。 Examples of the phosphorus component include phosphoric acid such as orthophosphoric acid (H 3 PO 4 ) and metaphosphoric acid (HPO 3 ), diammonium hydrogen phosphate ((NH 4 ) 2 HPO 4 ), and ammonium dihydrogen phosphate (NH 4 Examples thereof include ammonium hydrogen phosphate such as H 2 PO 4 ), and orthophosphoric acid, diammonium hydrogen phosphate, and ammonium dihydrogen phosphate are preferable because of relatively high purity and easy composition control.

Ａ成分としては、Ｃｏ、Ｎｉ、Ｍｎ、Ｆｅ、Ｃｕ、Ｃｒ各々の金属塩のうち１種が用いられ、例えば、Ｆｅ塩としては、硫酸鉄（II）（ＦｅＳＯ４）、酢酸鉄（II）（Ｆｅ（ＣＨ３ＣＯＯ）２）、塩化鉄（II）（ＦｅＣｌ２）等が好ましい。
Ｄ成分としては、Ｍｇ、Ｃａ、Ｆｅ、Ｎｉ、Ｃｏ、Ｍｎ、Ｚｎ、Ｇｅ、Ｃｕ、Ｃｒ、Ｔｉ、Ｓｒ、Ｂａ、Ｓｃ、Ｙ、Ａｌ、Ｇａ、Ｉｎ、Ｓｉ、Ｂ、希土類元素各々のうちＡ成分と異なる元素の金属塩のうち１種または２種以上が用いられ、例えば、Ａｌ２（ＳＯ４）３、ＭｇＳＯ４、Ｔｉ（ＳＯ４）２等の硫酸塩、Ａｌ（ＣＨ３ＣＯＯ）３、Ｍｇ（ＣＨ３ＣＯＯ）２等の酢酸塩、ＡｌＣｌ３、ＣａＣｌ２、ＴｉＣｌ４等の塩化物等の金属塩が好ましい。 As the A component, one of metal salts of Co, Ni, Mn, Fe, Cu, and Cr is used. For example, as the Fe salt, iron (II) sulfate (FeSO 4 ), iron (II) acetate. (Fe (CH 3 COO) 2 ), iron chloride (II) (FeCl 2 ) and the like are preferable.
As D component, Mg, Ca, Fe, Ni, Co, Mn, Zn, Ge, Cu, Cr, Ti, Sr, Ba, Sc, Y, Al, Ga, In, Si, B, each of rare earth elements One or more metal salts of elements different from the component A are used. For example, sulfates such as Al 2 (SO 4 ) 3 , MgSO 4 , Ti (SO 4 ) 2 , Al (CH 3 COO) 3 , and metal salts such as acetates such as Mg (CH 3 COO) 2 and chlorides such as AlCl 3 , CaCl 2 , and TiCl 4 are preferable.

水に可溶な有機酸としては、ヒドロキシカルボン酸またはカルボン酸が好ましく、例えば、ヒドロキシカルボン酸としては、クエン酸、リンゴ酸、乳酸、酒石酸等が挙げられ、カルボン酸としては、マロン酸、アクリル酸、ポリアクリル酸、メタクリル酸、ギ酸、マレイン酸、コハク酸等が挙げられる。   As the organic acid soluble in water, hydroxycarboxylic acid or carboxylic acid is preferable. Examples of the hydroxycarboxylic acid include citric acid, malic acid, lactic acid, tartaric acid, and the like, and examples of the carboxylic acid include malonic acid and acrylic acid. Examples include acid, polyacrylic acid, methacrylic acid, formic acid, maleic acid, and succinic acid.

中でも、クエン酸は、次のＡ、Ｂの２つの理由により、特に好適である。
（Ａ）金属イオンに対するキレート効果が高いことから、生じたＬｉＦｅＰＯ４等のＬｉｘＡｙＤｚＰＯ４結晶核の成長を抑制する。
（Ｂ）分解時に還元性を示すため、Ａ成分やＢ成分の酸化を防止する。例えば、Ａ成分としてＦｅを用いる場合、Ｆｅの２価から３価への酸化を防止する。
この有機酸は、Ｌｉ成分、Ｐ成分、Ａ成分及びＤ成分を加えて出発原料を調整する際に、これらの成分と同時に添加してもよく、これらの成分を混合した後に添加してもよい。 Among these, citric acid is particularly suitable for the following two reasons A and B.
(A) Since the chelating effect on metal ions is high, the growth of Li x A y D z PO 4 crystal nuclei such as LiFePO 4 is suppressed.
(B) Since it shows reducibility at the time of decomposition, oxidation of A component and B component is prevented. For example, when Fe is used as the A component, oxidation of Fe from divalent to trivalent is prevented.
This organic acid may be added simultaneously with these components when adding the Li component, P component, A component and D component to adjust the starting material, or may be added after mixing these components. .

水を主成分とする溶媒としては、純水、水−アルコール溶液、水−ケトン溶液、水−エーテル溶液等が挙げられ、中でも純水が好ましい。
その理由は、水は安価であり、臨界点付近で誘電率の大きな変化を示すことから、温度、圧力の操作により容易に各物質に対する溶解度等の溶媒物性を制御することが可能だからである。 Examples of the solvent containing water as a main component include pure water, a water-alcohol solution, a water-ketone solution, and a water-ether solution. Among these, pure water is preferable.
The reason is that water is inexpensive and exhibits a large change in dielectric constant near the critical point, so that it is possible to easily control solvent physical properties such as solubility in each substance by manipulating temperature and pressure.

次いで、この出発原料溶液を加圧下にて加熱する。加圧下にて加熱する方法は特に限定されないが、通常、出発原料溶液を耐圧容器に収納し、加熱することにより行う。
上記の様にして調整された出発原料を耐圧容器に収納し、その後、加熱して所定の最高保持温度まで昇温させ、この最高保持温度にて所定の時間保持することにより合成反応を進行させ、その後、室温（２５℃）まで降温させる。 The starting material solution is then heated under pressure. The method of heating under pressure is not particularly limited, but it is usually performed by storing the starting material solution in a pressure resistant container and heating.
The starting material adjusted as described above is stored in a pressure vessel, and then heated to raise the temperature to a predetermined maximum holding temperature, and the synthesis reaction proceeds by holding at this maximum holding temperature for a predetermined time. Thereafter, the temperature is lowered to room temperature (25 ° C.).

この反応条件は、溶媒の種類や合成する物質に応じて適宜選択されるが、本発明の製造方法では、リチウム金属リン酸化合物微粒子を合成する際に、高温にしたり、長時間反応させたりしても粒子が粗大化する虞がないので、反応条件を比較的自由に設定することができる。例えば、溶媒が純水の場合、最高保持温度が１２０〜２００℃、保持時間（反応時間）が１〜１２時間程度で、結晶性に優れたリチウム金属リン酸化合物微粒子を合成することができる。   The reaction conditions are appropriately selected according to the type of solvent and the substance to be synthesized. In the production method of the present invention, when the lithium metal phosphate compound fine particles are synthesized, the reaction temperature is increased or the reaction is performed for a long time. However, the reaction conditions can be set relatively freely because there is no risk of coarsening of the particles. For example, when the solvent is pure water, it is possible to synthesize lithium metal phosphate fine particles having excellent crystallinity with a maximum holding temperature of 120 to 200 ° C. and a holding time (reaction time) of about 1 to 12 hours.

次いで、耐圧容器内の生成物を濾過により分離・回収し、水洗後乾燥することにより、ＬｉｘＡｙＤｚＰＯ４（但し、ＡはＣｏ、Ｎｉ、Ｍｎ、Ｆｅ、Ｃｕ、Ｃｒから選択された１種、ＤはＭｇ、Ｃａ、Ｆｅ、Ｎｉ、Ｃｏ、Ｍｎ、Ｚｎ、Ｇｅ、Ｃｕ、Ｃｒ、Ｔｉ、Ｓｒ、Ｂａ、Ｓｃ、Ｙ、Ａｌ、Ｇａ、Ｉｎ、Ｓｉ、Ｂ、希土類元素から選択された１種または２種以上かつ前記Ａと異なる、０≦ｘ＜２、０＜ｙ＜１．５、０≦ｚ＜１．５）にて表されるリチウム電池用正極活物質が得られる。 Next, the product in the pressure vessel is separated and recovered by filtration, washed with water, and dried to obtain Li x A y D z PO 4 (where A is selected from Co, Ni, Mn, Fe, Cu, Cr). D is selected from Mg, Ca, Fe, Ni, Co, Mn, Zn, Ge, Cu, Cr, Ti, Sr, Ba, Sc, Y, Al, Ga, In, Si, B, and rare earth elements The positive electrode active material for a lithium battery represented by one or two or more of the above and different from A is represented by 0 ≦ x <2, 0 <y <1.5, 0 ≦ z <1.5) is obtained. .

このリチウム電池用正極活物質は、固相法に比べて比較的低温で合成され、かつ溶解と析出の条件を制御することが可能であるから、例えば、平均一次粒子径が０．０１〜１０μｍのリチウム電池用正極活物質微粒子が得られる。合成条件をさらに制御することにより、例えば、平均一次粒子径が０．０２〜１μｍのリチウム電池用正極活物質微粒子が得られる。   This positive electrode active material for a lithium battery is synthesized at a relatively low temperature as compared with the solid phase method, and the conditions for dissolution and precipitation can be controlled. For example, the average primary particle diameter is 0.01 to 10 μm. The positive electrode active material fine particles for lithium battery can be obtained. By further controlling the synthesis conditions, for example, positive electrode active material fine particles for lithium batteries having an average primary particle size of 0.02 to 1 μm can be obtained.

このリチウム電池用正極活物質微粒子の平均一次粒子径が０．０１μｍより小さいと、Ｌｉの挿入・脱離に伴う構造変化により粒子が破壊し、また、表面積が大きすぎるために結合剤を多く必要とし、その結果、正極合剤の導電率が低くなり、正極の充填密度が著しく低下する。また、その平均一次粒子径が１０μｍより大きいと、正極活物質の内部抵抗が高くなり、Ｌｉイオンの物質移動も遅延するために、利用率が低下し、また、得られる粒子の比表面積が小さくなり、単位重量当たりの充放電容量が低下する。また、充放電の繰り返しにより粒子が破壊され、電池容量が低下する等の問題もある。
これにより、より高出力を得るためには、活物質の内部抵抗の影響が小さい０．０２〜１μｍの粒子が好ましい。 If the average primary particle size of the positive electrode active material fine particles for lithium batteries is smaller than 0.01 μm, the particles break down due to structural changes accompanying Li insertion / desorption, and the surface area is too large, so a large amount of binder is required. As a result, the conductivity of the positive electrode mixture is lowered, and the packing density of the positive electrode is significantly reduced. Further, if the average primary particle diameter is larger than 10 μm, the internal resistance of the positive electrode active material is increased, and the mass transfer of Li ions is also delayed, so that the utilization rate is lowered and the specific surface area of the obtained particles is small. Thus, the charge / discharge capacity per unit weight is reduced. In addition, there is a problem that particles are destroyed by repeated charge and discharge, and the battery capacity is reduced.
Thereby, in order to obtain a higher output, particles of 0.02 to 1 μm that are less affected by the internal resistance of the active material are preferable.

一般に、固相法の場合、結晶性を上げるためには、加熱温度を高くしたり、加熱時間を延長する必要があるが、この場合、加熱過程で粒子同士が融着したり、あるいは粒子が異常粒成長することにより、粗大な粒子が生じる虞があり、粒径の制御は容易ではない。
本実施形態の製造方法では、固相法に比べて比較的低温で合成することができ、しかも溶解と析出の条件を制御することができるので、例えば、平均一次粒子径が０．０１〜１０μｍ、好ましくは０．０２〜１μｍの高結晶性のリチウム電池用正極活物質微粒子を得ることができ、したがって、リチウム電池用正極活物質微粒子の表面積を大きくすることができる。 In general, in the case of the solid phase method, in order to increase crystallinity, it is necessary to increase the heating temperature or extend the heating time. In this case, the particles are fused with each other in the heating process, or the particles are not bonded. Abnormal grain growth may cause coarse particles, and control of the particle size is not easy.
In the production method of the present embodiment, synthesis can be performed at a relatively low temperature compared to the solid phase method, and the dissolution and precipitation conditions can be controlled. For example, the average primary particle size is 0.01 to 10 μm. In addition, it is possible to obtain positive electrode active material fine particles for lithium battery, preferably having a high crystallinity of 0.02 to 1 μm, and therefore the surface area of the positive electrode active material fine particles for lithium battery can be increased.

また、このリチウム電池用正極活物質微粒子をリチウム二次電池に適用することで、高い充放電速度を有するリチウム二次電池を実現することができる。
また、固相法の場合、比較的高温で所定時間保持する必要があるが、本実施形態の製造方法の場合、固相法に比べて少ないエネルギーで反応を進行させることができるので、ランニングコスト面でも有利である。 Moreover, the lithium secondary battery which has a high charging / discharging rate is realizable by applying this positive electrode active material microparticle for lithium batteries to a lithium secondary battery.
Further, in the case of the solid phase method, it is necessary to hold for a predetermined time at a relatively high temperature. However, in the case of the manufacturing method of the present embodiment, the reaction can proceed with less energy than the solid phase method, so that the running cost is reduced. This is also advantageous.

以上により、本実施形態の製造方法によれば、その反応中に原料成分を全て溶解し、溶解−再析出過程を含むため、大きさが均一な結晶核を合成することができる。したがって、この結晶核を基に微粒子を成長させることで、この微粒子の平均一次粒子径、結晶化度等を制御することができる。また、反応過程では、一度溶解した後に析出により粒子化するので、結晶成長の方向を制御することができ、結晶成長の方向が揃った微粒子を合成することができ、また、粒子形状の制御も可能である。   As described above, according to the manufacturing method of the present embodiment, since all the raw material components are dissolved during the reaction and the dissolution-reprecipitation process is included, crystal nuclei having a uniform size can be synthesized. Therefore, by growing fine particles based on the crystal nuclei, the average primary particle diameter, crystallinity, etc. of the fine particles can be controlled. In the reaction process, once dissolved, the particles are formed by precipitation, so that the direction of crystal growth can be controlled, fine particles with the same direction of crystal growth can be synthesized, and the shape of the particles can be controlled. Is possible.

以下、実施例及び比較例１、２により本発明を具体的に説明するが、本発明はこれらの実施例によって限定されるものではない。
（実施例）
０．２ｍｏｌの酢酸リチウム（ＬｉＣＨ３ＣＯＯ）、０．１ｍｏｌの硫酸鉄（II）（ＦｅＳＯ４）、０．１ｍｏｌのオルトリン酸（Ｈ３ＰＯ４）、０．１ｍｏｌのクエン酸及び純水を、総量が０．２リットル（Ｌ）となる様に混合し、均一な透明溶液を得た。得られた溶液を容量０．３Ｌの耐圧密閉容器に収納し、１７０℃にて３時間保持し、反応させた。その後、この耐圧密閉容器内の生成物を濾過により分離・回収し、水洗後乾燥し、試料１を得た。 EXAMPLES Hereinafter, although an Example and Comparative Examples 1 and 2 demonstrate this invention concretely, this invention is not limited by these Examples.
(Example)
0.2 mol of lithium acetate (LiCH 3 COO), 0.1 mol of iron (II) sulfate (FeSO 4 ), 0.1 mol of orthophosphoric acid (H 3 PO 4 ), 0.1 mol of citric acid and pure water, The mixture was mixed so that the total amount was 0.2 liter (L) to obtain a uniform transparent solution. The obtained solution was accommodated in a pressure-resistant airtight container having a capacity of 0.3 L, and kept at 170 ° C. for 3 hours to be reacted. Thereafter, the product in the pressure tight sealed container was separated and collected by filtration, washed with water and dried to obtain Sample 1.

（比較例１）
クエン酸を添加しない点以外は、実施例と同様にして試料２を得た。
（比較例２）
反応時間を６時間とした点以外は、比較例１と同様にして試料３を得た。 (Comparative Example 1)
Sample 2 was obtained in the same manner as in Example except that citric acid was not added.
(Comparative Example 2)
Sample 3 was obtained in the same manner as in Comparative Example 1 except that the reaction time was 6 hours.

実施例及び比較例１、２で得られた試料１〜３それぞれのＣｕ Ｋα Ｘ線による粉末Ｘ線回折図形を図１に示す。なお、図１の下端部には、ＪＣＰＤＳカード（♯８１−１１７３）に記載されているＬｉＦｅＰＯ４の回折線（２θ）を示してある。
また、実施例で得られた試料１の走査電子顕微鏡像（ＳＥＭ像）を図２に、比較例２で得られた試料３の走査電子顕微鏡像（ＳＥＭ像）を図３に、それぞれ示す。 The powder X-ray diffraction patterns by Cu Kα X-rays of Samples 1 to 3 obtained in Examples and Comparative Examples 1 and 2 are shown in FIG. In addition, the diffraction line (2θ) of LiFePO 4 described in the JCPDS card (# 81-1173) is shown at the lower end of FIG.
Moreover, the scanning electron microscope image (SEM image) of the sample 1 obtained in the Example is shown in FIG. 2, and the scanning electron microscope image (SEM image) of the sample 3 obtained in Comparative Example 2 is shown in FIG.

（リチウム電池の作製）
実施例および比較例１、２で得られた試料１〜３を基に実施例および比較例１、２のリチウム電池をそれぞれ作製した。
ここでは、試料１〜３各８５重量部と、導電助剤として平均一次粒子径が１４ｎｍ、比表面積が２９０ｍ２／ｇのカーボンブラック（ＣＢ）１０重量部を、ポリフッ化ビニリデン（ＰＶｄＦ）５重量部、Ｎ−メチル−２−ピロリジノン（ＮＭＰ）７０重量部と共に、三本ロール等を用いて混練・ペースト化し、厚みが３０μｍのアルミニウム箔上に塗布し、乾燥後、４０ＭＰａの圧力にて圧密し、正極とした。 (Production of lithium battery)
The lithium batteries of Examples and Comparative Examples 1 and 2 were produced based on Samples 1 to 3 obtained in Examples and Comparative Examples 1 and 2, respectively.
Here, 85 parts by weight of each of Samples 1 to 3, 10 parts by weight of carbon black (CB) having an average primary particle diameter of 14 nm and a specific surface area of 290 m 2 / g as a conductive assistant, and 5 parts by weight of polyvinylidene fluoride (PVdF) Together with 70 parts by weight of N-methyl-2-pyrrolidinone (NMP), kneaded and pasted using three rolls, etc., coated on an aluminum foil with a thickness of 30 μm, dried, and compacted at a pressure of 40 MPa A positive electrode was obtained.

次いで、これらの正極を真空乾燥器を用いて真空乾燥した後、乾燥したアルゴン雰囲気下にて２０１６型コインセルを用いて実施例および比較例１、２の電池を作製した。
ここでは、負極として金属Ｌｉを、セパレータとして多孔質ポリプロピレン膜を、電解質溶液として１ｍｏｌ／ＬのＬｉＰＦ６溶液を、それぞれ用いた。
なお、このＬｉＰＦ６溶液に用いられる溶媒としては、炭酸エチレンと炭酸メチルエチルを体積％で１：１に混合したものを用いた。 Next, these positive electrodes were vacuum-dried using a vacuum dryer, and then batteries of Examples and Comparative Examples 1 and 2 were fabricated using 2016 type coin cells in a dry argon atmosphere.
Here, metal Li was used as the negative electrode, a porous polypropylene film was used as the separator, and a 1 mol / L LiPF 6 solution was used as the electrolyte solution.
As the solvent used in this LiPF 6 solution, 1 ethylene carbonate and methyl ethyl carbonate in a volume%: was a mixture in 1.

（電池充放電試験）
実施例及び比較例１、２それぞれの電池に対して、室温（２５℃）にて電池充放電試験を行った。
この電池充放電試験においては、カットオフ電圧を２〜４．５Ｖとし、放充電の電流密度については、放充電共に電流量（レート：１Ｃ）の定電流とし、放充電のサイクルは、１時間で充電、１時間で放電とした。 (Battery charge / discharge test)
A battery charge / discharge test was performed at room temperature (25 ° C.) for each of the batteries of Examples and Comparative Examples 1 and 2.
In this battery charge / discharge test, the cut-off voltage is set to 2 to 4.5 V, and the current density of discharge / discharge is a constant current with a current amount (rate: 1C) for both discharge and charge, and the charge / discharge cycle is 1 hour. And charging in 1 hour.

上記の実施例及び比較例２それぞれの充放電試験結果を図４に示す。なお、比較例１については、Ｌｉ3ＰＯ4等の不純物相を多く含むために充放電試験を行うことができなかった。
また、実施例及び比較例１、２それぞれの結晶相、平均一次粒子径及び放電容量を表１に示す。 The charge / discharge test results of the above Examples and Comparative Example 2 are shown in FIG. In Comparative Example 1, the charge / discharge test could not be performed because it contained a large amount of impurity phase such as Li 3 PO 4 .
Table 1 shows the crystal phases, average primary particle diameters, and discharge capacities of Examples and Comparative Examples 1 and 2, respectively.

Figure 2005276474
Figure 2005276474

これらの結果によれば、実施例では、クエン酸を添加することにより微粒子化が可能となり、高出力での放電容量が大幅に向上していることが分かった。また、均一溶液（原子レベルで混合）にて反応が生じているため、より温和な条件で単相の結晶相が得られることが分かった。
一方、比較例１、２では、クエン酸を添加していないために、試料２、３中に原料混合時に生成したＬｉ３ＰＯ４や反応中間体が残っている、あるいは、粒子の粗大化が生じ、低い電極性能となることが分かった。 According to these results, it was found that the addition of citric acid enabled the formation of fine particles, and the discharge capacity at high output was greatly improved. It was also found that the reaction occurred in a homogeneous solution (mixed at the atomic level), so that a single-phase crystal phase was obtained under milder conditions.
On the other hand, in Comparative Examples 1 and 2, since citric acid was not added, Li 3 PO 4 and reaction intermediates produced during mixing of the raw materials remained in Samples 2 and 3 , or particle coarsening occurred. It was found that the electrode performance was low.

なお、本実施例では、本電極材料自体の挙動をデータに反映させるために、負極に金属Ｌｉを用いたが、負極材料は、金属Ｌｉの他、例えば、炭素材料、Ｌｉ合金、Ｌｉ４Ｔｉ５Ｏ１２等を用いてもよい。また、電解質溶液とセパレータの替わりに固体電解質を用いてもよい。 In this example, in order to reflect the behavior of the electrode material itself in the data, metal Li was used for the negative electrode, but the negative electrode material may be, for example, a carbon material, a Li alloy, Li 4 Ti other than metal Li. 5 O 12 or the like may be used. A solid electrolyte may be used instead of the electrolyte solution and the separator.

本発明は、リチウム電池用正極活物質微粒子を合成する際に、水に可溶な有機酸を加えることで、高結晶性かつ微粒子のＬｉｘＡｙＤｚＰＯ４が得られるものであるから、リチウム電池のさらなる充放電容量の向上、充放電サイクルの安定化、高出力化はもちろんのこと、さらなる小型化、軽量化、高容量化が期待される二次電池の分野に適用することが可能である。 In the present invention, when synthesizing positive electrode active material fine particles for a lithium battery, highly crystalline Li x A y D z PO 4 can be obtained by adding an organic acid soluble in water. In addition to improving the charge / discharge capacity of lithium batteries, stabilizing the charge / discharge cycle, and increasing output, it can be applied to the field of secondary batteries where further miniaturization, weight reduction, and higher capacity are expected. Is possible.

本発明の実施例及び比較例１、２で得られた試料１〜３それぞれの粉末Ｘ線回折図形を示す図である。It is a figure which shows the powder X-ray-diffraction figure of each of the samples 1-3 obtained by the Example of this invention and Comparative Examples 1 and 2. FIG. 本発明の実施例で得られた試料１の走査電子顕微鏡像（ＳＥＭ像）を示す図である。It is a figure which shows the scanning electron microscope image (SEM image) of the sample 1 obtained by the Example of this invention. 比較例２で得られた試料３の走査電子顕微鏡像（ＳＥＭ像）を示す図である。It is a figure which shows the scanning electron microscope image (SEM image) of the sample 3 obtained by the comparative example 2. FIG. 本発明の実施例及び比較例１、２それぞれの電池の放充電特性を示す図である。It is a figure which shows the charging / discharging characteristic of each battery of the Example of this invention and Comparative Examples 1 and 2.

Claims (8)

ＬｉｘＡｙＤｚＰＯ４（但し、ＡはＣｏ、Ｎｉ、Ｍｎ、Ｆｅ、Ｃｕ、Ｃｒから選択された１種、ＤはＭｇ、Ｃａ、Ｆｅ、Ｎｉ、Ｃｏ、Ｍｎ、Ｚｎ、Ｇｅ、Ｃｕ、Ｃｒ、Ｔｉ、Ｓｒ、Ｂａ、Ｓｃ、Ｙ、Ａｌ、Ｇａ、Ｉｎ、Ｓｉ、Ｂ、希土類元素から選択された１種または２種以上かつ前記Ａと異なる、０≦ｘ＜２、０＜ｙ＜１．５、０≦ｚ＜１．５）にて表されるリチウム電池用正極活物質の製造方法であって、
水を主成分とする溶媒に、リチウム（Ｌｉ）成分、リン（Ｐ）成分、前記Ａ成分、前記Ｄ成分及び水に可溶な有機酸を加え、次いで、この溶液を加圧下にて加熱することにより、前記ＬｉｘＡｙＤｚＰＯ４を生成することを特徴とするリチウム電池用正極活物質の製造方法。 Li x A y D z PO 4 (where A is one selected from Co, Ni, Mn, Fe, Cu, Cr, D is Mg, Ca, Fe, Ni, Co, Mn, Zn, Ge, Cu) , Cr, Ti, Sr, Ba, Sc, Y, Al, Ga, In, Si, B, one or more selected from rare earth elements and different from A, 0 ≦ x <2, 0 <y <1.5, 0 ≦ z <1.5), a method for producing a positive electrode active material for a lithium battery,
A lithium (Li) component, a phosphorus (P) component, the A component, the D component and an organic acid soluble in water are added to a solvent containing water as a main component, and then the solution is heated under pressure. it allows the Li x a y D z PO 4 method for producing a cathode active material for lithium battery and generates a. 前記有機酸は、ヒドロキシカルボン酸またはカルボン酸であることを特徴とする請求項１記載のリチウム電池用正極活物質の製造方法。   The method for producing a positive electrode active material for a lithium battery according to claim 1, wherein the organic acid is hydroxycarboxylic acid or carboxylic acid. 前記ヒドロキシカルボン酸は、クエン酸、リンゴ酸、乳酸、酒石酸の群から選択された１種または２種以上であることを特徴とする請求項２記載のリチウム電池用正極活物質の製造方法。   The method for producing a positive electrode active material for a lithium battery according to claim 2, wherein the hydroxycarboxylic acid is one or more selected from the group consisting of citric acid, malic acid, lactic acid, and tartaric acid. 前記Ａは、Ｃｏ、Ｎｉ、Ｍｎ、Ｆｅから選択された１種であることを特徴とする請求項１、２または３記載のリチウム電池用正極活物質の製造方法。   The said A is 1 type selected from Co, Ni, Mn, and Fe, The manufacturing method of the positive electrode active material for lithium batteries of Claim 1, 2 or 3 characterized by the above-mentioned. 前記Ｄは、Ｍｇ、Ｃａ、Ｎｉ、Ｃｏ、Ｍｎ、Ｚｎ、Ｔｉ、Ａｌから選択された１種または２種以上であることを特徴とする請求項１ないし４のいずれか１項記載のリチウム電池用正極活物質の製造方法。   5. The lithium battery according to claim 1, wherein the D is one or more selected from Mg, Ca, Ni, Co, Mn, Zn, Ti, and Al. For producing a positive electrode active material for use. 請求項１ないし５のいずれか１項記載のリチウム電池用正極活物質の製造方法により得られたことを特徴とするリチウム電池用正極活物質。   A positive electrode active material for a lithium battery obtained by the method for producing a positive electrode active material for a lithium battery according to any one of claims 1 to 5. 請求項６記載のリチウム電池用正極活物質を含有してなることを特徴とするリチウム電池用電極。   An electrode for a lithium battery comprising the positive electrode active material for a lithium battery according to claim 6. 請求項７記載のリチウム電池用電極を正電極として備えてなることを特徴とするリチウム電池。   A lithium battery comprising the lithium battery electrode according to claim 7 as a positive electrode.
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WO2010005095A1 (en) * 2008-07-09 2010-01-14 住友化学株式会社 Nonaqueous electrolyte secondary battery
JP2010232091A (en) * 2009-03-27 2010-10-14 Sumitomo Osaka Cement Co Ltd Method for manufacturing positive active material for lithium ion battery, positive active material for lithium ion battery, electrode for lithium ion battery, and lithium ion battery
WO2011078195A1 (en) * 2009-12-24 2011-06-30 住友化学株式会社 Method for producing electrode, method for producing electrode paste, and sodium secondary battery
US8097362B2 (en) 2007-02-19 2012-01-17 Toyota Jidosha Kabushiki Kaisha Electrode active material and manufacturing method of same
WO2012008532A1 (en) * 2010-07-16 2012-01-19 三菱化学株式会社 Positive electrode for lithium secondary batteries and lithium secondary battery using same
JP2013525974A (en) * 2010-04-21 2013-06-20 エルジー・ケム・リミテッド Cathode active material for secondary battery and lithium secondary battery including the same

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US8097362B2 (en) 2007-02-19 2012-01-17 Toyota Jidosha Kabushiki Kaisha Electrode active material and manufacturing method of same
WO2010005095A1 (en) * 2008-07-09 2010-01-14 住友化学株式会社 Nonaqueous electrolyte secondary battery
JP2010020987A (en) * 2008-07-09 2010-01-28 Sumitomo Chemical Co Ltd Non-aqueous electrolyte secondary battery
JP2010232091A (en) * 2009-03-27 2010-10-14 Sumitomo Osaka Cement Co Ltd Method for manufacturing positive active material for lithium ion battery, positive active material for lithium ion battery, electrode for lithium ion battery, and lithium ion battery
WO2011078195A1 (en) * 2009-12-24 2011-06-30 住友化学株式会社 Method for producing electrode, method for producing electrode paste, and sodium secondary battery
JP2011134550A (en) * 2009-12-24 2011-07-07 Sumitomo Chemical Co Ltd Method of manufacturing electrode and electrode paste, and sodium secondary battery
JP2013525974A (en) * 2010-04-21 2013-06-20 エルジー・ケム・リミテッド Cathode active material for secondary battery and lithium secondary battery including the same
WO2012008532A1 (en) * 2010-07-16 2012-01-19 三菱化学株式会社 Positive electrode for lithium secondary batteries and lithium secondary battery using same

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