JP2011014369A - Method for producing positive electrode active material particles - Google Patents

Method for producing positive electrode active material particles Download PDF

Info

Publication number
JP2011014369A
JP2011014369A JP2009157188A JP2009157188A JP2011014369A JP 2011014369 A JP2011014369 A JP 2011014369A JP 2009157188 A JP2009157188 A JP 2009157188A JP 2009157188 A JP2009157188 A JP 2009157188A JP 2011014369 A JP2011014369 A JP 2011014369A
Authority
JP
Japan
Prior art keywords
active material
electrode active
positive electrode
material particles
battery
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP2009157188A
Other languages
Japanese (ja)
Other versions
JP5332965B2 (en
Inventor
Motofumi Isono
基史 磯野
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toyota Motor Corp
Original Assignee
Toyota Motor Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toyota Motor Corp filed Critical Toyota Motor Corp
Priority to JP2009157188A priority Critical patent/JP5332965B2/en
Publication of JP2011014369A publication Critical patent/JP2011014369A/en
Application granted granted Critical
Publication of JP5332965B2 publication Critical patent/JP5332965B2/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing positive electrode active material particles, in which a cell can be composed by using an easy to handle material in a negative electrode side, to provide such positive electrode active material particles, and to provide a lithium ion secondary battery comprising such positive electrode active material particles in a positive electrode active material layer.SOLUTION: The method for producing positive electrode active material particles 1 constituted of amorphous LiFePO(0<x≤2.5, 0<y≤2) comprises a synthesis step of synthesizing the positive electrode active material particles 1 by a sol-gel process. In the synthesis step, the positive electrode active material particles 1 are synthesized in an acid solution with a hydrogen ion exponent (pH) of 4.0 or less.

Description

本発明は、非晶質の正極活物質粒子の製造方法に関する。   The present invention relates to a method for producing amorphous positive electrode active material particles.

近年、ハイブリッド車やノート型パソコン、ビデオカムコーダなどのポータブル電子機器の駆動用電源に、リチウムイオン二次電池（以下、単に電池ともいう）が利用されている。
このような電池には、非晶質の正極活物質粒子を用いるものが挙げられる。例えば特許文献１においては、ＬｉxＭｎ2-yＭyＯ4（Ｍは２価金属，０．４５≦ｙ≦０．６０，０≦ｘ≦１）で表される正極（正極活物質粒子）を、ゾルゲル法を用いて製造する技術が開示されている。また、特許文献２においては、７Ａ族及び８Ａ族の少なくとも１種の遷移金属の酸化物により構成され、その一部がアモルファス構造を有する正極活物質（正極活物質粒子）が開示されている。この特許文献２では、正極活物質粒子を製造する手法として、溶融状態から急冷凝固させる溶融急冷法や、ゾルゲル法が、例示されている。 In recent years, lithium ion secondary batteries (hereinafter also simply referred to as batteries) have been used as power sources for driving portable electronic devices such as hybrid cars, notebook computers, and video camcorders.
Such batteries include those using amorphous positive electrode active material particles. For example, in Patent Document 1, a positive electrode (positive electrode active material particle) represented by Li x Mn 2 -y My O 4 (M is a divalent metal, 0.45 ≦ y ≦ 0.60, 0 ≦ x ≦ 1) ) Is manufactured using a sol-gel method. Patent Document 2 discloses a positive electrode active material (positive electrode active material particles) that is composed of an oxide of at least one transition metal of Group 7A and Group 8A, part of which has an amorphous structure. In Patent Document 2, as a method for producing positive electrode active material particles, a melt quench method in which a solid is rapidly solidified from a molten state and a sol-gel method are exemplified.

特表２０００−５１５６７２号公報JP 2000-515672 A 特開平８−７８００２号公報JP-A-8-78002

ところで、正極活物質として、非晶質のＬｉxＦｅＰyＯz（０＜ｘ≦２．５，０＜ｙ≦２）が好ましいことが判ってきた。
しかるに、このＬｉxＦｅＰyＯzにおけるＦｅは２価及び３価を取りうる。このようなＬｉxＦｅＰyＯzのうちＬｉＦｅＰＯzにおいて、２価のＦｅを含むＬｉＦｅＰＯzからなる正極活物質では、これを正極活物質層に含む電池について充電すると、
ＬｉＦｅＰＯz → ＦｅＰＯz＋Ｌｉ+＋ｅ- ・・・式（１）
で示すように、Ｆｅの価数が２価から３価に換わって、正極活物質からＬｉイオンが放出されることが知られている。これを放電させると、式（１）と逆の化学変化が生じる。従って、充放電とも、正極活物質が本来有していたＬｉイオンを用いることになる。但し、まず当初に充電を行う必要がある。 By the way, it has been found that amorphous Li x FeP y O z (0 <x ≦ 2.5, 0 <y ≦ 2) is preferable as the positive electrode active material.
However, Fe in this Li x FeP y O z can be divalent and trivalent. Among such Li x FeP y O z , in LiFePO z , in a positive electrode active material made of LiFePO z containing divalent Fe, when charging a battery including this in the positive electrode active material layer,
LiFePO z → FePO z + Li + + e − (1)
It is known that the valence of Fe changes from divalent to trivalent, and Li ions are released from the positive electrode active material. When this is discharged, a chemical change opposite to the formula (1) occurs. Therefore, Li ion originally possessed by the positive electrode active material is used for both charging and discharging. However, it is necessary to charge first.

一方、３価のＦｅを含むＬｉＦｅＰＯzからなる正極活物質では、既にＦｅの価数が３価であるので、上述の式（１）のような化学変化を伴う充電をすることはできない。即ち、この３価のＦｅを含む正極活物質からは、Ｌｉイオンを放出することができない。但し、例えば負極などに、別途、Ｌｉイオンが存在する場合には、放電と共に、このＬｉイオンを正極活物質に挿入する化学変化を生じさせうる。即ち、放電により、下記の式（２）の反応が生じ、Ｆｅの価数が３価から２価に換わると共にＬｉイオンが正極活物質に挿入される。
ＬｉＦｅＰＯz＋Ｌｉ+＋ｅ- → Ｌｉ2ＦｅＰＯz ・・・式（２）
とはいえ、この場合には、別途、負極活物質に予めＬｉを挿入しておくなど、Ｌｉを含む負極を用いる必要がある。しかし、Ｌｉイオンを含む負極を用いうるのであれば、当初に放電から始めることができる。 On the other hand, in the positive electrode active material composed of LiFePO z containing trivalent Fe, since already the valence of Fe is trivalent, it is not possible to charge with a chemical change, such as the above equation (1). That is, Li ions cannot be released from the positive electrode active material containing trivalent Fe. However, for example, when Li ions are separately present in the negative electrode or the like, a chemical change in which the Li ions are inserted into the positive electrode active material can be caused along with the discharge. That is, by the discharge, the reaction of the following formula (2) occurs, the valence of Fe is changed from trivalent to divalent, and Li ions are inserted into the positive electrode active material.
LiFePO z + Li + + e − → Li 2 FePO z (2)
However, in this case, it is necessary to separately use a negative electrode containing Li, such as inserting Li in advance in the negative electrode active material. However, if a negative electrode containing Li ions can be used, the discharge can be started from the beginning.

なお、このＬｉxＦｅＰyＯzにおけるＦｅの平均価数が、２．０を超え３．０未満の値である場合には、２価のＦｅを含むＬｉxＦｅＰyＯzと、３価のＦｅを含むＬｉxＦｅＰyＯzとが混在していると考えることができる。従って、ＬｉxＦｅＰyＯzにおけるＦｅの平均価数が２．０に近い正極活物質ほど、式（１）に従って、充電によって３価に換わることが可能な２価のＦｅをより多く含むことになる。逆に、Ｆｅの平均価数が３に近い正極活物質ほど、ＬｉxＦｅＰyＯzとは別に、負極側により多くのＬｉイオンを予め挿入しておく必要があることになる。つまり、負極活物質に、Ｌｉイオンをより多く挿入した、取り扱いの困難な材料を用いなければならない。 In addition, when the average valence number of Fe in Li x FeP y O z is a value exceeding 2.0 and less than 3.0, Li x FeP y O z containing divalent Fe and trivalent It can be considered that Li x FeP y O z containing Fe is mixed. Therefore, as the cathode active material near the Li x FeP y O z average valence of Fe in 2.0, according to equation (1), that contain more divalent Fe capable to replace the trivalent by the charging become. On the contrary, the positive electrode active material having an average Fe valence of 3 needs to insert more Li ions in advance on the negative electrode side separately from Li x FeP y O z . That is, it is necessary to use a material that is difficult to handle, in which more Li ions are inserted into the negative electrode active material.

しかしながら、このＬｉxＦｅＰyＯzからなる正極活物質粒子をゾルゲル法で製造すると、この正極活物質粒子を用いた電池では、負極（負極活物質）には、Ｌｉイオンをより多く挿入した、取り扱いの困難な材料を用いなければならない場合がある。この場合には、Ｆｅの平均価数が３．０に近い正極活物質粒子ができてしまうためであると考えられる。また、正極活物質中のＬｉのほかに、別途負極にもＬｉが必要となり、Ｌｉの利用効率が低いうえに、コストが増大してしまう。 However, when producing a positive electrode active material particles composed of the Li x FeP y O z by a sol-gel method, in the battery using the positive electrode active material particles, the negative electrode (negative electrode active material) was inserted more Li ions, It may be necessary to use materials that are difficult to handle. In this case, it is considered that positive electrode active material particles having an average valence number of Fe close to 3.0 are formed. In addition to Li in the positive electrode active material, Li is also required for the negative electrode separately, which lowers the utilization efficiency of Li and increases the cost.

本発明は、かかる問題点に鑑みてなされたものであって、取り扱いの容易な材料を負極側に用いて電池を構成することができる正極活物質粒子の製造方法を提供することを目的とする。   This invention is made | formed in view of this problem, Comprising: It aims at providing the manufacturing method of the positive electrode active material particle which can comprise a battery using the material which is easy to handle for the negative electrode side. .

本発明の一態様は、非晶質のＬｉxＦｅＰyＯz（０＜ｘ≦２．５，０＜ｙ≦２）からなる正極活物質粒子の製造方法であって、ゾルゲル法により上記正極活物質粒子を合成する合成工程を備え、上記合成工程は、水素イオン指数（ｐＨ）を４．０以下とした酸性溶液中で、上記正極活物質粒子を合成する正極活物質粒子の製造方法である。 One aspect of the present invention is a method for producing positive electrode active material particles made of amorphous Li x FeP y O z (0 <x ≦ 2.5, 0 <y ≦ 2). A synthesis step of synthesizing active material particles, wherein the synthesis step is a method for producing positive electrode active material particles in which the positive electrode active material particles are synthesized in an acidic solution having a hydrogen ion index (pH) of 4.0 or less. is there.

発明者らの研究により、水素イオン指数（ｐＨ）を４．０以下とした酸性溶液中で、非晶質のＬｉxＦｅＰyＯzからなる正極活物質粒子を合成すると、この正極活物質粒子を用いた電池では、負極に挿入するＬｉイオンを低減或いはなくすことができることが判ってきた。これは、このＬｉxＦｅＰyＯzのうちＦｅの平均価数が２．０に近づけることができると考えられる。
この知見に基づき、この正極活物質粒子の製造方法では、ｐＨを４．０以下とした酸性溶液中で、正極活物質粒子を合成する。このため、平均価数が２．０に近づけた、ＬｉxＦｅＰyＯzからなる正極活物質粒子を製造できる。従って、電池に、この正極活物質粒子と共に、Ｌｉイオンを低減させた、取り扱いの容易な材料を負極に用いることができる。 According to the inventors' research, positive electrode active material particles made of amorphous Li x FeP y O z were synthesized in an acidic solution having a hydrogen ion index (pH) of 4.0 or less. It has been found that in a battery using, Li ions inserted into the negative electrode can be reduced or eliminated. This is considered that the average valence of Fe in Li x FeP y O z can approach 2.0.
Based on this knowledge, in the method for producing positive electrode active material particles, the positive electrode active material particles are synthesized in an acidic solution having a pH of 4.0 or less. For this reason, positive electrode active material particles made of Li x FeP y O z with an average valence approaching 2.0 can be produced. Therefore, an easy-to-handle material with reduced Li ions can be used for the negative electrode together with the positive electrode active material particles.

なお、平均価数とは、正極活物質粒子をなすＬｉxＦｅＰyＯzの各Ｆｅの価数の平均値をいう。また、正極活物質粒子におけるＦｅの平均価数を検知する手法としては、例えば、メスバウワー分光法が挙げられる。 The average valence refers to a valence of the average value of each Fe in Li x FeP y O z forming a positive electrode active material particles. An example of a method for detecting the average valence number of Fe in the positive electrode active material particles is Mossbauer spectroscopy.

さらに、上述の正極活物質粒子の製造方法であって、前記合成工程は、水素イオン指数（ｐＨ）を３．４以下とした酸性溶液中で、上記正極活物質粒子を合成する正極活物質粒子の製造方法とすると良い。   Furthermore, in the method for producing the positive electrode active material particles described above, the synthesis step includes synthesizing the positive electrode active material particles in an acidic solution having a hydrogen ion index (pH) of 3.4 or less. It is good to use this manufacturing method.

上述の正極活物質粒子の製造方法によれば、Ｆｅの平均価数をほぼ２．０とすることができると考えられる。従って、電池に、この正極活物質粒子と共に、Ｌｉイオンを含まない、取り扱いの容易な材料を負極に用いることができる。   According to the method for producing positive electrode active material particles described above, it is considered that the average valence number of Fe can be made approximately 2.0. Therefore, an easy-to-handle material that does not contain Li ions can be used for the negative electrode together with the positive electrode active material particles.

実施形態１のリチウムイオン二次電池の斜視図である。1 is a perspective view of a lithium ion secondary battery according to Embodiment 1. FIG. 実施形態１のリチウムイオン二次電池の拡大断面図である。1 is an enlarged cross-sectional view of a lithium ion secondary battery according to Embodiment 1. FIG. 実施形態１にかかる正極活物質粒子の合成工程を示すフローチャートである。3 is a flowchart illustrating a synthesis process of positive electrode active material particles according to the first embodiment. 正極活物質粒子の合成時の水素イオン指数（ｐＨ）と、合成した正極活物質粒子と用いたリチウムイオン二次電池における初回の充放電効率との関係を示すグラフである。It is a graph which shows the relationship between the hydrogen ion index | exponent (pH) at the time of the synthesis | combination of positive electrode active material particle | grains, and the initial charging / discharging efficiency in the lithium ion secondary battery using the synthesized positive electrode active material particle | grains.

（実施形態１）
まず、本発明の実施形態１について、図面を参照しつつ説明する。
図１は、本実施形態１のリチウムイオン二次電池１００（以下、単に電池１００とも言う）であり、図１は、この電池１００の斜視図、図２は、この電池１００の拡大縦断面図である。
この電池１００は、正極活物質粒子１を主体に圧縮成形してなる正極活物質層１０のほか、電池ケース５０、負極活物質層２０、セパレータ３０及び電解液（図示しない）からなる、リチウムイオン二次電池である。 (Embodiment 1)
First, Embodiment 1 of the present invention will be described with reference to the drawings.
FIG. 1 shows a lithium ion secondary battery 100 (hereinafter also simply referred to as battery 100) according to Embodiment 1, FIG. 1 is a perspective view of the battery 100, and FIG. 2 is an enlarged longitudinal sectional view of the battery 100. It is.
The battery 100 includes a positive electrode active material layer 10 formed mainly by compression molding of the positive electrode active material particles 1, a lithium ion including a battery case 50, a negative electrode active material layer 20, a separator 30, and an electrolyte (not shown). It is a secondary battery.

このうち、電池ケース５０は、ステンレス鋼板からなり、底部５１ａが円形の概略コイン形状を有している。この電池ケース５０は、容器体５１と蓋体５２とを有する。このうち、容器体５１は、円板状の底部５１ａ、及び、この周縁からこれに直交する方向に立ち上がり、先端側が内側に曲げられると共に縮径する形態の円筒壁部５１ｂからなる。
また、蓋体５２は円板形状を有し、円筒壁部５１ｂの先端で構成される開口部５１ｃを封口してなる。これら容器体５１と蓋体５２との間には、絶縁体のガスケット５３が介在しており、容器体５１が正極端子を、蓋体５２が負極端子をそれぞれ兼ねている。 Among these, the battery case 50 is made of a stainless steel plate, and the bottom 51a has a substantially coin shape with a circular shape. The battery case 50 includes a container body 51 and a lid body 52. Among these, the container body 51 includes a disk-shaped bottom portion 51a and a cylindrical wall portion 51b that rises from the peripheral edge in a direction perpendicular to the peripheral edge and bends inward while being reduced in diameter.
The lid 52 has a disk shape and is formed by sealing an opening 51c formed by the tip of the cylindrical wall 51b. An insulating gasket 53 is interposed between the container body 51 and the lid body 52. The container body 51 also serves as a positive electrode terminal, and the lid body 52 serves as a negative electrode terminal.

この電池ケース５０の内部には、正極活物質層１０及び負極活物質層２０が、セパレータ３０を介して、図２中、上下方向に積層してある（図２参照）。なお、正極活物質層１０は容器体５１の底部５１ａ側に、負極活物質層２０は蓋体５２側にそれぞれ配置されると共に、電気的に接続している。   Inside the battery case 50, the positive electrode active material layer 10 and the negative electrode active material layer 20 are stacked in the vertical direction in FIG. 2 via the separator 30 (see FIG. 2). The positive electrode active material layer 10 is disposed on the bottom 51a side of the container body 51, and the negative electrode active material layer 20 is disposed on the lid body 52 side, and is electrically connected.

次いで、正極活物質層１０について説明する。この正極活物質層１０は、正極活物質粒子１、アセチレンブラック（ＡＢ）からなる導電助剤５、及び、ポリテトラフルオロエチレン（ＰＴＦＥ）からなる結着剤６の混合物を円板状に圧縮成形したものである。
一方、負極活物質層２０には、グラファイトからなる負極活物質粒子８、及び、アセチレンブラック（ＡＢ）からなる導電助剤５を、円板状に圧縮成形したものを用いた。また、セパレータ３０としては、多孔質ポリエチレンシートを用いた。さらに、電解液としては、エチレンカーボネートとジエチルカーボネートとの体積比１：１の混合溶媒に、１モル／ｌの濃度でＬｉＰＦ6を溶解させたものを使用した。この電解液は、上述のセパ
レータ３０に含浸されている。
また、この正極活物質層１０の正極活物質粒子１は、粒径が数百ｎｍで非晶質のＬｉ2ＦｅＰ1.5Ｏzからなる。 Next, the positive electrode active material layer 10 will be described. This positive electrode active material layer 10 is formed by compression-molding a mixture of positive electrode active material particles 1, a conductive additive 5 made of acetylene black (AB), and a binder 6 made of polytetrafluoroethylene (PTFE) into a disk shape. It is a thing.
On the other hand, for the negative electrode active material layer 20, a negative electrode active material particle 8 made of graphite and a conductive additive 5 made of acetylene black (AB) were compression-molded into a disk shape. As the separator 30, a porous polyethylene sheet was used. Further, as the electrolytic solution, a solution obtained by dissolving LiPF 6 at a concentration of 1 mol / l in a mixed solvent of ethylene carbonate and diethyl carbonate in a volume ratio of 1: 1 was used. This electrolytic solution is impregnated in the separator 30 described above.
The positive electrode active material particles 1 of the positive electrode active material layer 10 are made of amorphous Li 2 FeP 1.5 O z having a particle size of several hundred nm.

次いで、本実施形態１にかかる正極活物質粒子１の製造方法の合成工程について、図３を参照しつつ説明する。
まず、ステップＳ１において、２００ｍｌの水に、Ｃ4Ｈ6Ｏ4Ｆｅを０．１０ｍｏｌ／ｌ、Ｃ2Ｈ3ＬｉＯ2・２Ｈ2Ｏを０．２０ｍｏｌ／ｌ、及び、ＮＨ4Ｈ2ＰＯ4を０．１５ｍｏｌ／ｌを原料としてそれぞれ投入した。さらに、この水溶液中に、シュウ酸（Ｃ2Ｈ4Ｏ3）を０．５０ｍｏｌ／ｌを投入し、この水溶液の水素イオン指数（ｐＨ）を３．５に調整した。そして、オイルバスでこの水溶液を４８時間、８０℃に保持した。
次いで、液温を８０℃としたまま水溶液から２４時間かけて水を飛散、粉末状の析出物を得た（ステップＳ２）。 Next, a synthesis process of the method for producing the positive electrode active material particles 1 according to the first embodiment will be described with reference to FIG.
First, in step S1, C 4 H 6 O 4 Fe 0.10 mol / l, C 2 H 3 LiO 2 .2H 2 O 0.20 mol / l, and NH 4 H 2 PO 4 in 200 ml of water. Of 0.15 mol / l was added as a raw material. Furthermore, 0.50 mol / l of oxalic acid (C 2 H 4 O 3 ) was added to this aqueous solution, and the hydrogen ion index (pH) of this aqueous solution was adjusted to 3.5. And this aqueous solution was hold | maintained at 80 degreeC for 48 hours with the oil bath.
Next, water was scattered from the aqueous solution over 24 hours while keeping the liquid temperature at 80 ° C. to obtain a powdery precipitate (step S2).

続いて、ステップＳ３では、析出物を、１１０℃で４８時間、乾燥を行った。具体的には、１１０℃に加熱した乾燥炉中で、４８時間乾燥させた。
さらに、ステップＳ４で、４００℃の温度で焼成した。具体的には、アルゴン雰囲気中で、昇温速度を毎分１℃で４００℃まで昇温させ、その後、４００℃を５時間維持させた。かくして、本実施形態１にかかる正極活物質粒子１ができあがる。 Subsequently, in step S3, the precipitate was dried at 110 ° C. for 48 hours. Specifically, it was dried for 48 hours in a drying furnace heated to 110 ° C.
Further, in step S4, firing was performed at a temperature of 400 ° C. Specifically, in an argon atmosphere, the temperature rising rate was raised to 400 ° C. at 1 ° C. per minute, and then maintained at 400 ° C. for 5 hours. Thus, the positive electrode active material particles 1 according to the first embodiment are completed.

一方、上述の正極活物質粒子１の比較例として、上述のステップＳ１において、水素イオン濃度（ｐＨ）を３．５位に調整するためのシュウ酸（Ｃ2Ｈ4Ｏ3）を投入しない点で異なる、正極活物質粒子２を製造した。
即ち、２００ｍｌの水に、Ｃ4Ｈ6Ｏ4Ｆｅを０．１０ｍｏｌ／ｌ、Ｃ2Ｈ3ＬｉＯ2・２Ｈ2Ｏを０．２０ｍｏｌ／ｌ、及び、ＮＨ4Ｈ2ＰＯ4を０．１５ｍｏｌ／ｌを原料としてそれぞれ投入した。このときの水溶液の水素イオン指数（ｐＨ）は５．０であった。そして、オイルバスでこの水溶液を４８時間、８０℃に保持した。
次いで、８０℃としたまま水溶液から２４時間かけて水を飛散させ、その後、１１０℃で４８時間、乾燥を行った。さらに、４００℃の温度で焼成して、正極活物質粒子２を製造した。 On the other hand, as a comparative example of the positive electrode active material particles 1 described above, in the above-described step S1, oxalic acid (C 2 H 4 O 3 ) for adjusting the hydrogen ion concentration (pH) to the 3.5 position is not added. Different positive electrode active material particles 2 were produced.
That is, 0.10 mol / l of C 4 H 6 O 4 Fe, 0.20 mol / l of C 2 H 3 LiO 2 .2H 2 O, and 0.15 mol of NH 4 H 2 PO 4 in 200 ml of water. / L was used as a raw material. The hydrogen ion exponent (pH) of the aqueous solution at this time was 5.0. And this aqueous solution was hold | maintained at 80 degreeC for 48 hours with the oil bath.
Next, water was spattered from the aqueous solution over 24 hours while maintaining the temperature at 80 ° C., followed by drying at 110 ° C. for 48 hours. Furthermore, the positive electrode active material particles 2 were manufactured by firing at a temperature of 400 ° C.

これら正極活物質粒子１，正極活物質粒子２をそれぞれ用いて作製した電池Ｃ１及び電池Ｃ２について、合成時の水溶液の水素イオン指数（ｐＨ）と初回の充放電効率との関係を調査した。
具体的には、各電池Ｃ１，Ｃ２、初回の充電（即ち、各電池Ｃ１，Ｃ２を製造して最初の充電）と、その後の放電とを行って、初回の充放電効率をそれぞれ算出した。なお、充電は、電池Ｃ１，Ｃ２の各電圧がそれぞれ４．５Ｖになるまで、一定の大きさの電流（電流密度が０．２ｍＡ／ｃｍ2の電流）で充電した。また、放電は、電池Ｃ１，Ｃ２の各電圧がそれぞれ１．５Ｖになるまで、一定の大きさの電流（電流密度が０．２ｍＡ／ｃｍ2の電流）で放電させた。
さらに、初回の充放電効率は、上述した放電時の電流積算量を、充電時の電流積算量で割った百分率で表す。
各電池Ｃ１，Ｃ２の合成時の水溶液の水素イオン指数（ｐＨ）と、初回の充放電効率との関係を、図４に示す。 The relationship between the hydrogen ion index (pH) of the aqueous solution at the time of synthesis and the initial charge / discharge efficiency was investigated for the battery C1 and the battery C2 produced using the positive electrode active material particles 1 and the positive electrode active material particles 2, respectively.
Specifically, each battery C1, C2, first charge (that is, first charge after manufacturing each battery C1, C2) and subsequent discharge were performed, and the first charge / discharge efficiency was calculated. The charging was performed with a constant current (current having a current density of 0.2 mA / cm 2 ) until each voltage of the batteries C1 and C2 became 4.5V. Further, the discharge was performed with a constant current (current density of 0.2 mA / cm 2 ) until each voltage of the batteries C1 and C2 became 1.5V.
Further, the initial charge / discharge efficiency is expressed as a percentage obtained by dividing the above-described current integrated amount during discharging by the current integrated amount during charging.
FIG. 4 shows the relationship between the hydrogen ion exponent (pH) of the aqueous solution at the time of synthesis of the batteries C1 and C2 and the initial charge / discharge efficiency.

この図４によると、電池Ｃ２の充放電効率は４２０％である。即ち、初回の充電時に正極側から放出したＬｉイオンの量よりも、放電時に負極側から放出したＬｉイオンの量の方が約４．２倍多いことが判る。これに対し、電池Ｃ１の充放電効率が１１０％であり、初回の充電時に正極側から放出したＬｉイオンの量と、放電時に負極側から放出したＬｉイオンの量とがほぼ等しいことが判る。
これは、電池Ｃ２の正極活物質粒子２におけるＦｅの平均価数が３．０に近いために、電池Ｃ２では、前述の式（１）に従う化学反応がわずかしか生じず、すぐに満充電となると考えられる。一方、放電時には、式（１）と逆方向の化学変化のほかに、負極（金属リチウム箔）のＬｉを用いて、前述の式（２）の化学変化も生じたと考えられる。 According to FIG. 4, the charge / discharge efficiency of the battery C2 is 420%. That is, it can be seen that the amount of Li ions released from the negative electrode side during discharge is about 4.2 times greater than the amount of Li ions released from the positive electrode side during the first charge. On the other hand, the charge / discharge efficiency of the battery C1 is 110%, and it can be seen that the amount of Li ions released from the positive electrode side during the first charge and the amount of Li ions released from the negative electrode side during the discharge are substantially equal.
This is because the average valence number of Fe in the positive electrode active material particles 2 of the battery C2 is close to 3.0, so that in the battery C2, the chemical reaction according to the above formula (1) occurs only slightly, It is considered to be. On the other hand, during the discharge, in addition to the chemical change in the direction opposite to the formula (1), it is considered that the chemical change of the formula (2) described above also occurred using Li of the negative electrode (metal lithium foil).

これに対し、電池Ｃ１では、これに用いた正極活物質粒子１におけるＦｅの平均価数が２．０に近いために、電池Ｃ１では、用いた正極活物質粒子１のほぼ全量について、式（１）の化学反応をさせて充電し、これと逆の反応によって放電を行うことができると考えられる。このため、充放電とも、もともと正極活物質が有していたＬｉイオンを用いて行うことができる。かくして、初回の放電にあたって、正極活物質由来とは別に、予めＬｉを負極に持たせておく必要がなく、Ｌｉの利用効率も高い。   On the other hand, in the battery C1, since the average valence of Fe in the positive electrode active material particles 1 used for the battery C1 is close to 2.0, in the battery C1, the expression ( It is considered that the chemical reaction of 1) can be performed for charging, and discharging can be performed by the reverse reaction. For this reason, both charge and discharge can be performed using Li ions originally possessed by the positive electrode active material. Thus, in the first discharge, it is not necessary to have Li in advance in the negative electrode separately from the positive electrode active material, and the utilization efficiency of Li is high.

また、この図４から判るように、合成時の水溶液のｐＨが３〜５の範囲では、このｐＨが小さいほど、初回の充放電効率が急速に１００％に近くなる。正極活物質粒子のＦｅの平均価数が２．０である場合には、初回の充放電効率が１００％となることから、合成時の水溶液のｐＨが小さくなるほど、正極活物質粒子のＦｅの平均価数が２．０に近づくことが考えられる。この図４から、合成時のｐＨを３．４以下とすることで、確実にＦｅの平均価数を２．０とすることができることが判る。
また、図４から、ｐＨを４．０以下とした水溶液中でＬｉ2ＦｅＰ1.5Ｏzを合成すれば、正極活物質粒子のＦｅの平均価数を２．０に近づけることができることが判る。 Further, as can be seen from FIG. 4, when the pH of the aqueous solution at the time of synthesis is in the range of 3 to 5, the first charge / discharge efficiency rapidly approaches 100% as the pH decreases. When the average valence of Fe of the positive electrode active material particles is 2.0, the initial charge / discharge efficiency is 100%. Therefore, the lower the pH of the aqueous solution during synthesis, the lower the Fe of the positive electrode active material particles. It is conceivable that the average valence approaches 2.0. It can be seen from FIG. 4 that the average valence of Fe can be reliably set to 2.0 by setting the pH during synthesis to 3.4 or less.
In addition, it can be seen from FIG. 4 that if Li 2 FeP 1.5 O z is synthesized in an aqueous solution having a pH of 4.0 or less, the average valence of Fe of the positive electrode active material particles can be made close to 2.0.

以上より、正極活物質粒子１の製造方法として、ｐＨを４．０以下（本実施形態１では３．５）とした酸性溶液中で、正極活物質粒子１を合成する。このため、Ｆｅの平均価数が２．０に近づけたＬｉ2ＦｅＰ1.5Ｏzからなる正極活物質粒子１を製造できる。従って、電池１００に、この正極活物質粒子１を用いることで、予めドープしたＬｉの量を低減させた、取り扱いの容易な材料を負極活物質層２０に用いることができる。 From the above, as a method for producing the positive electrode active material particles 1, the positive electrode active material particles 1 are synthesized in an acidic solution having a pH of 4.0 or lower (3.5 in the present embodiment 1). Thus, it can be produced a positive electrode active material particles 1 having an average valence of Fe consists Li 2 FeP 1.5 O z as close to 2.0. Therefore, by using the positive electrode active material particles 1 for the battery 100, an easily handled material in which the amount of previously doped Li is reduced can be used for the negative electrode active material layer 20.

また、この製造方法において、水素イオン指数（ｐＨ）を３．４以下とすれば、Ｆｅの平均価数をほぼ２．０とすることができると考えられる。従って、電池１００に、この正極活物質粒子１と共に、Ｌｉイオンを含まない、取り扱いの容易な材料（グラファイト等）を負極活物質層２０に用いることができる。   In this production method, if the hydrogen ion index (pH) is 3.4 or less, it is considered that the average valence of Fe can be made approximately 2.0. Therefore, an easy-to-handle material (such as graphite) that does not contain Li ions can be used for the negative electrode active material layer 20 together with the positive electrode active material particles 1 in the battery 100.

以上において、本発明を実施形態１に即して説明したが、本発明は上記実施形態に限定されるものではなく、その要旨を逸脱しない範囲で、適宜変更して適用できることは言うまでもない。
例えば、Ｌｉ2ＦｅＰ1.5Ｏzからなる正極活物質粒子１の合成工程では、Ｆｅの原料としてＣ4Ｈ6Ｏ4Ｆｅを、Ｌｉの原料としてＣ2Ｈ3ＬｉＯ2・２Ｈ2Ｏを、Ｐの原料としてＮＨ4Ｈ2ＰＯ4をそれぞれ用いた。しかし、このうちのＦｅの原料として、例えば、Ｆｅ（ＯＣ2Ｈ5）3を用いても良い。また、Ｌｉの原料として、例えば、ＬｉＯＣＨ3を用いても良い。また、Ｐの原料として、例えば、ＰＯ（ＯＣＨ3）3を用いても良い。
また、実施形態１の合成工程では、処理時間や設定温度等の条件を示したが、これに限定されず、例えば、正極活物質粒子に用いる原料によって条件の少なくともいずれかを変更しても良い。 While the present invention has been described with reference to the first embodiment, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be appropriately modified and applied without departing from the gist thereof.
For example, in the step of synthesizing the positive electrode active material particles 1 made of Li 2 FeP 1.5 O z , C 4 H 6 O 4 Fe is used as a raw material for Fe, C 2 H 3 LiO 2 .2H 2 O is used as a raw material for Li, P NH 4 H 2 PO 4 was used as a raw material for each. However, for example, Fe (OC 2 H 5 ) 3 may be used as a raw material for Fe. Further, for example, LiOCH 3 may be used as a Li source. Moreover, as a raw material of P, for example, PO (OCH 3 ) 3 may be used.
In the synthesis process of Embodiment 1, conditions such as processing time and set temperature are shown. However, the present invention is not limited to this. For example, at least one of the conditions may be changed depending on the raw material used for the positive electrode active material particles. .

１ 正極活物質粒子
１０ 正極活物質層
１００ 電池（リチウムイオン二次電池） DESCRIPTION OF SYMBOLS 1 Positive electrode active material particle 10 Positive electrode active material layer 100 Battery (lithium ion secondary battery)

Claims (2)

非晶質のＬｉxＦｅＰyＯz（０＜ｘ≦２．５，０＜ｙ≦２）からなる正極活物質粒子の製造方法であって、
ゾルゲル法により上記正極活物質粒子を合成する合成工程を備え、
上記合成工程は、
水素イオン指数（ｐＨ）を４．０以下とした酸性溶液中で、上記正極活物質粒子を合成する
正極活物質粒子の製造方法。 A method for producing positive electrode active material particles composed of amorphous Li x FeP y O z (0 <x ≦ 2.5, 0 <y ≦ 2),
Comprising a synthesis step of synthesizing the positive electrode active material particles by a sol-gel method,
The above synthesis process
A method for producing positive electrode active material particles, wherein the positive electrode active material particles are synthesized in an acidic solution having a hydrogen ion index (pH) of 4.0 or less. 請求項１に記載の正極活物質粒子の製造方法であって、
前記合成工程は、
水素イオン指数（ｐＨ）を３．４以下とした酸性溶液中で、上記正極活物質粒子を合成する
正極活物質粒子の製造方法。 It is a manufacturing method of the positive electrode active material particle of Claim 1, Comprising:
The synthesis step includes
A method for producing positive electrode active material particles, wherein the positive electrode active material particles are synthesized in an acidic solution having a hydrogen ion index (pH) of 3.4 or less.
JP2009157188A 2009-07-01 2009-07-01 Method for producing positive electrode active material particles Active JP5332965B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2009157188A JP5332965B2 (en) 2009-07-01 2009-07-01 Method for producing positive electrode active material particles

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2009157188A JP5332965B2 (en) 2009-07-01 2009-07-01 Method for producing positive electrode active material particles

Publications (2)

Publication Number Publication Date
JP2011014369A true JP2011014369A (en) 2011-01-20
JP5332965B2 JP5332965B2 (en) 2013-11-06

Family

ID=43593058

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2009157188A Active JP5332965B2 (en) 2009-07-01 2009-07-01 Method for producing positive electrode active material particles

Country Status (1)

Country Link
JP (1) JP5332965B2 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011113857A (en) * 2009-11-27 2011-06-09 Toyota Motor Corp Method of manufacturing electrode active material
JP2012226916A (en) * 2011-04-18 2012-11-15 Sharp Corp Cathode active material and manufacturing method thereof, cathode, and nonaqueous electrolyte secondary battery
WO2014155408A1 (en) * 2013-03-25 2014-10-02 株式会社豊田自動織機 Hydrogen-containing lithium silicate compound, process for producing same, positive active material for nonaqueous-electrolyte secondary battery, positive electrode for nonaqueous-electrolyte secondary battery, and nonaqueous-electrolyte secondary battery

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003200051A (en) * 2001-12-28 2003-07-15 Sony Corp Catalyst for oxygen oxidation-reduction device and electrode using the same
WO2008105490A1 (en) * 2007-02-28 2008-09-04 Santoku Corporation Compound having olivine-type structure, positive electrode for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery
JP2009527085A (en) * 2006-02-14 2009-07-23 ハイ パワー リチウム ソシエテ アノニム Lithium manganese phosphate cathode material for lithium secondary battery

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003200051A (en) * 2001-12-28 2003-07-15 Sony Corp Catalyst for oxygen oxidation-reduction device and electrode using the same
JP2009527085A (en) * 2006-02-14 2009-07-23 ハイ パワー リチウム ソシエテ アノニム Lithium manganese phosphate cathode material for lithium secondary battery
WO2008105490A1 (en) * 2007-02-28 2008-09-04 Santoku Corporation Compound having olivine-type structure, positive electrode for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
JPN7011003921; Ｋｕｅｉ-Ｆｅｎｇ　Ｈｓｕ，ｅｔ．ａｌ: 'Ｓｙｎｔｈｅｓｉｓ　ａｎｄ　ｃｈａｒａｃｔｅｒｉｚａｔｉｏｎ　ｏｆ　ｎａｎｏ-ｓｉｚｅｄ　ＬｉＦｅＰＯ４　ｃａｔｈｏｄｅ　ｍａｔｅｒｉａｌｓ　ｐｒｅｐａｒｅｄ　ｂｙ　ａ　ｃｉｔｒｉｃ　ａｃｉｄ-ｂａｓ' Ｊ．Ｍａｔｅｒ．Ｃｈｅｍ １４, 20040701, ２６９０-２６９５, ＲＳＣ *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011113857A (en) * 2009-11-27 2011-06-09 Toyota Motor Corp Method of manufacturing electrode active material
JP2012226916A (en) * 2011-04-18 2012-11-15 Sharp Corp Cathode active material and manufacturing method thereof, cathode, and nonaqueous electrolyte secondary battery
WO2014155408A1 (en) * 2013-03-25 2014-10-02 株式会社豊田自動織機 Hydrogen-containing lithium silicate compound, process for producing same, positive active material for nonaqueous-electrolyte secondary battery, positive electrode for nonaqueous-electrolyte secondary battery, and nonaqueous-electrolyte secondary battery

Also Published As

Publication number Publication date
JP5332965B2 (en) 2013-11-06

Similar Documents

Publication Publication Date Title
KR100674287B1 (en) Layered core·shell cathode active materials for lithium secondary batteries, Method for preparing thereof And lithium secondary batteries using the same
KR101338816B1 (en) Positive electrode materials combining high safety and high power in a li rechargeable battery
KR101447453B1 (en) Positive electrode active material for nonaqueous electrolyte secondary battery, positive electrode and secondary battery
EP2237348B1 (en) Positive electrode material for lithium secondary battery, lithium secondary battery, and secondary battery module using lithium secondary battery
KR101430843B1 (en) Positive electrode active material for lithium-ion battery, positive electrode for lithium-ion battery, and lithium-ion battery
KR101378580B1 (en) Cathod active material, lithium rechargeble battery including the same, and method of activiting the same
TWI446611B (en) Non-homogeneous positive electrode materials combining high safety and high power in a li rechargeable battery
US8968925B2 (en) Metal-doped transition metal hexacyanoferrate (TMHCF) battery electrode
CN107534143B (en) Positive electrode active material, method for producing same, and nonaqueous electrolyte secondary battery
US20110121226A1 (en) Method for manufacturing lithium titanate for lithium secondary battery active material
CN107922212B (en) Manganese-nickel composite hydroxide and method for producing same, lithium-manganese-nickel composite oxide and method for producing same, and nonaqueous electrolyte secondary battery
KR20170139462A (en) Anode active material for sodium secondary battery, and manufacturing method therefor
KR102044735B1 (en) Layered lithium nickel oxide, process for producing the same and lithium secondary cell employing it
JP5516463B2 (en) Method for producing positive electrode active material for lithium ion secondary battery
WO2003069701A1 (en) Production methods for positive electrode active matter and non-aqueous electrolytic battery
KR20180043842A (en) Lithium metal oxide material, its use in an anode of a secondary battery, and a method of producing such a lithium metal oxide material
KR20170100529A (en) Lithium-cobalt composite oxide, production method therefor, electrochemical device, and lithium ion secondary battery
JP5332965B2 (en) Method for producing positive electrode active material particles
KR102220491B1 (en) Positive active materials for rechargable lithium battery, method of preparing the same and rechargable lithium battery using the same
JP6362033B2 (en) Cathode active material for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery
WO2016103558A1 (en) Lithium-phosphorus composite oxide carbon composite, production method therefor, electrochemical device, and lithium ion secondary battery
CN111373583A (en) Positive electrode active material for lithium ion secondary battery and method for producing same
JP2019212365A (en) Positive electrode active material for lithium ion secondary battery and manufacturing method thereof, and lithium ion secondary battery using the same
US11855284B2 (en) Positive electrode active material precursor for non-aqueous electrolyte secondary battery
US11873234B2 (en) Positive electrode active material precursor for non-aqueous electrolyte secondary battery, and method of manufacturing positive electrode active material precursor for non-aqueous electrolyte secondary battery

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20120118

TRDD Decision of grant or rejection written
A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20130628

A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20130702

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20130715

R151 Written notification of patent or utility model registration

Ref document number: 5332965

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R151