JP5517032B2 - Non-aqueous electrolyte secondary battery olivine-type composite oxide particle powder, method for producing the same, and secondary battery - Google Patents
Non-aqueous electrolyte secondary battery olivine-type composite oxide particle powder, method for producing the same, and secondary battery Download PDFInfo
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Description
本発明は、非水電解質二次電池の正極活物質に用いるオリビン型複合酸化物粒子粉末であり、充放電容量が大きく、充填性に優れた正極を提供できるオリビン型複合酸化物粒子粉末に関する。 The present invention relates to an olivine-type composite oxide particle powder used as a positive electrode active material for a non-aqueous electrolyte secondary battery, which can provide a positive electrode having a large charge / discharge capacity and excellent fillability.
近年、ＡＶ機器やパソコン等の電子機器のポータブル化、コードレス化が急速に進んでおり、これらの駆動用電源として小型、軽量で高エネルギー密度を有する二次電池への要求が高くなっている。また、近年地球環境への配慮から、電気自動車、ハイブリッド自動車の開発及び実用化がなされ、大型用途として保存特性の優れたリチウムイオン二次電池への要求が高くなっている。このような状況下において、充放電容量が大きく、安全性が高いという長所を有するリチウムイオン二次電池が注目されている。 In recent years, electronic devices such as AV devices and personal computers are rapidly becoming portable and cordless, and there is an increasing demand for secondary batteries having a small size, light weight, and high energy density as power sources for driving these devices. In recent years, in consideration of the global environment, electric vehicles and hybrid vehicles have been developed and put into practical use, and the demand for a lithium ion secondary battery having excellent storage characteristics as a large-scale application is increasing. Under such circumstances, a lithium ion secondary battery having advantages such as a large charge / discharge capacity and high safety has attracted attention.
最近、３．５Ｖ級の電圧をもつ高エネルギー型のリチウムイオン二次電池に有用な正極活物質として、オリビン型構造を有するＬｉＦｅＰＯ４が高い充放電容量を有する電池として注目されてきている。しかし、この材料は、電気抵抗が本質的に大きく、電極としての充填性が悪い為、特性改善が求められている。 Recently, LiFePO 4 having an olivine structure has attracted attention as a battery having a high charge / discharge capacity as a positive electrode active material useful for a high energy type lithium ion secondary battery having a voltage of 3.5 V class. However, since this material has essentially high electrical resistance and poor filling properties as an electrode, improvement in characteristics is required.
即ち、オリビン型ＬｉＦｅＰＯ４は、強固なりん酸４面体骨格と酸化還元に寄与する鉄イオンを中心にもつ酸素８面体とリチウムイオンから構成される。この結晶構造ため、充放電反応を繰り返すことによっても結晶構造は安定であり、サイクル特性は劣化しない特長がある。しかしリチウムイオンの移動経路が一次元的であることや自由電子が少ないという欠点が存在する。この課題を解決する為に、オリビン型ＬｉＦｅＰＯ４の一部にＭｎ，Ｍｇ，Ｚｒ，Ｎｂ等を添加した材料の研究が行われてきたが、未だにこれらの課題を解決した材料は得られておらず、より電気抵抗の小さなものが求められている。 That is, olivine-type LiFePO 4 is composed of a strong phosphoric acid tetrahedral skeleton, an oxygen octahedron centered on iron ions contributing to redox, and lithium ions. Due to this crystal structure, the crystal structure is stable even when the charge / discharge reaction is repeated, and the cycle characteristics are not deteriorated. However, there are drawbacks in that the movement path of lithium ions is one-dimensional and there are few free electrons. In order to solve this problem, research has been conducted on materials in which Mn, Mg, Zr, Nb, etc. are added to a part of olivine-type LiFePO 4 , but no material that has solved these problems has yet been obtained. However, there is a demand for a material having a smaller electric resistance.
またＬｉＦｅＰＯ４は、粉末を構成する一次粒子径が小さいほど、高レートでの充放電特性がよい特徴があるので、オリビン型ＬｉＦｅＰＯ４を用いて優れた特性を有する正極を得るには、オリビン型ＬｉＦｅＰＯ４が密に凝集した二次粒子であって、かつカーボンのような低電気抵抗物質でネットワークを形成するように集合状態を制御する必要がある。しかし、カーボン等と複合化された正極活物質はかさ高く、単位体積当たりに充填できる実質的なリチウムイオン密度が低くなるといった欠点がある。そこで、単位体積当たりの充放電容量を確保するためには、不純物が少なく電気抵抗の小さなオリビン型ＬｉＦｅＰＯ４を得ると共に、小さな結晶子サイズの一次粒子が電気抵抗の小さな導電性補助剤を介して高い密度を持った二次集合体を形成することが一般的に必要とされている。 In addition, LiFePO 4 has a characteristic that the smaller the primary particle size constituting the powder, the better the charge / discharge characteristics at a high rate. Therefore, in order to obtain a positive electrode having excellent characteristics using olivine-type LiFePO 4 , the olivine type It is necessary to control the aggregated state so that LiFePO 4 is a densely aggregated secondary particle and a network is formed with a low electrical resistance material such as carbon. However, the positive electrode active material compounded with carbon or the like is bulky and has a drawback that the substantial lithium ion density that can be filled per unit volume is lowered. Therefore, in order to ensure the charge / discharge capacity per unit volume, olivine-type LiFePO 4 having a small amount of impurities and a small electric resistance is obtained, and primary particles having a small crystallite size are passed through a conductive auxiliary agent having a small electric resistance. There is a general need to form secondary aggregates with high density.
また、オリビン型ＬｉＦｅＰＯ４複合酸化物の製造方法において、充填性が高く非晶質部分が少なく、小さな一次結晶子を得るためには、固相反応性の高い微粒子で、不純物量を制御した鉄系含水酸化物粒子を用い、低温で短時間での条件で焼成を行う必要がある。 In addition, in the method for producing an olivine-type LiFePO 4 composite oxide, in order to obtain a small primary crystallite having a high filling property and a small amount of an amorphous part, iron having a controlled solid content and fine particles having high solid phase reactivity. It is necessary to perform firing at low temperature in a short time using the system hydrous oxide particles.
即ち、非水電解質二次電池用の正極活物質として充填性が高く不純物結晶相が少なく、電気抵抗の小さなオリビン型ＬｉＦｅＰＯ４複合酸化物を環境負荷が小さな工業的な方法で生産することが要求されている。 That is, it is required to produce an olivine-type LiFePO 4 composite oxide having a high filling property, a small impurity crystal phase, and a low electrical resistance as a positive electrode active material for a non-aqueous electrolyte secondary battery by an industrial method with a low environmental load. Has been.
従来、オリビン型ＬｉＦｅＰＯ４複合酸化物の諸特性改善のために、種々の改良が行われている。例えば、オリビン型ＬｉＦｅＰＯ４のＦｅサイトに他種金属を添加し、電気抵抗を低減する技術（特許文献１）、オリビン型ＬｉＦｅＰＯ４の製造時にタップ密度を向上させ、カーボンとの複合体を形成する技術（特許文献２）、酸化鉄原料を使用して優れた正極活物質を得る技術（特許文献３）、価数３の鉄化合物を凝集させたものを原料とする技術（特許文献４）、水熱法により微粒子オリビン型ＬｉＦｅＰＯ４粒子を合成する技術（非特許文献１）等が知られている。 Conventionally, various improvements have been made to improve various characteristics of the olivine-type LiFePO 4 composite oxide. For example, a technique (Patent Document 1) for adding other kinds of metals to the Fe site of olivine-type LiFePO 4 to reduce electrical resistance, and improving the tap density during the production of olivine-type LiFePO 4 to form a composite with carbon Technology (Patent Document 2), Technology for obtaining an excellent positive electrode active material using an iron oxide raw material (Patent Document 3), Technology using an agglomerated iron compound having a valence of 3 as a raw material (Patent Document 4), A technique for synthesizing fine olivine-type LiFePO 4 particles by a hydrothermal method (Non-Patent Document 1) is known.
非水電解質二次電池用の正極活物質として前記諸特性を満たすオリビン型ＬｉＦｅＰＯ４の複合酸化物粉末の製造方法について、現在最も要求されているところであるが、未だ確立されていない。 As a positive electrode active material for a non-aqueous electrolyte secondary battery, a method for producing a composite oxide powder of olivine-type LiFePO 4 that satisfies the above-mentioned characteristics is currently most demanded, but has not been established yet.
即ち、特許文献１記載の技術は、オリビン型ＬｉＦｅＰＯ４の複合酸化物の構造安定化や電気抵抗を提言するために他種金属を添加するという技術であり、電極への充填性や二次集合状態の制御については触れられていない。 In other words, the technique described in Patent Document 1 is a technique in which another metal is added in order to propose structural stabilization and electrical resistance of the olivine-type LiFePO 4 composite oxide. There is no mention of state control.
また、特許文献２記載の技術は、オリビン型ＬｉＦｅＰＯ４の複合酸化物の製造にカーボンとの集合体を形成する技術であるが、一次粒子のサイズ制御やカーボンとの複合体の集合状態の制御が難しいという欠点がある。また製造工程が長いために、金属粉末等のコンタミネーションを生じる危険性がある。 The technique described in Patent Document 2 is a technique for forming an aggregate with carbon in the production of a composite oxide of olivine-type LiFePO 4 , but controlling the size of primary particles and the aggregate state of the composite with carbon. Has the disadvantage of being difficult. Moreover, since the manufacturing process is long, there is a risk of causing contamination such as metal powder.
更に、特許文献３記載の技術は、原料として使用する酸化鉄の固相反応性が十分でないので、微細な一次粒子を合成することが困難である。 Furthermore, the technique described in Patent Document 3 is difficult to synthesize fine primary particles because the solid phase reactivity of iron oxide used as a raw material is not sufficient.
更に、特許文献４記載の技術は、汎用で安価な３価の鉄化合物を原料として、粒子形状を保持しながら、合成反応を遂行できる技術であるが、微小なビーズミルを使用して酸化鉄などの原料を混合・粉砕処理するために、粉砕力が大きく無視できないコンタミネーションが発生し、また使用する酸化鉄粒子が大きく固相反応時のイオン拡散効率が低い。 Furthermore, the technique described in Patent Document 4 is a technique that can perform a synthesis reaction while maintaining a particle shape using a general-purpose and inexpensive trivalent iron compound as a raw material. Since the raw materials are mixed and pulverized, contamination with a large pulverizing force is generated, and the iron oxide particles used are large and the ion diffusion efficiency during the solid phase reaction is low.
更に、非特許文献１記載の技術は、湿式法による合成技術により微粒子オリビン型ＬｉＦｅＰＯ４の複合酸化物の合成について述べているが、原料に硫酸鉄を用いているため、Ｓが残存し易く、硫酸リチウムなどの不純物を形成し、充放電中にそれらの不純物が分解反応を起こして、高温保存時の電解液との反応が促進され保存後の抵抗上昇が激しくなる。また、Ｌｉ原料比がＦｅ，Ｐに比べて３倍のモル比であるため、Ｌｉ損失が大きく、環境負荷が大きい。 Furthermore, the technology described in Non-Patent Document 1 describes the synthesis of a composite oxide of fine-particle olivine-type LiFePO 4 by a synthesis technique using a wet method. However, since iron sulfate is used as a raw material, S tends to remain, Impurities such as lithium sulfate are formed, and these impurities undergo a decomposition reaction during charging and discharging, and the reaction with the electrolytic solution during high temperature storage is promoted, and the resistance increase after storage becomes severe. Further, since the Li raw material ratio is three times the molar ratio of Fe and P, the Li loss is large and the environmental load is large.
そこで、本発明は、充填性が高く不純物結晶相が少ないオリビン型ＬｉＦｅＰＯ４の環境負荷が小さな効率的な工業的手法を確立することを技術的課題とする。 Therefore, the present invention has a technical problem to establish an efficient industrial method with a small environmental load of olivine type LiFePO 4 having a high filling property and a small impurity crystal phase.
前記技術的課題は、次の通りの本発明によって達成できる。 The technical problem can be achieved by the present invention as follows.
即ち、本発明は、組成がＬｉｘＦｅ１−ｙＭｙＰＯ４（０．８＜ｘ＜１．３、０≦ｙ＜０．３、Ｍ：Ｍｇ、Ｚｒ、Ｍｎ、Ａｌ、Ｔｉ、Ｃｅ、Ｃｒ、Ｃｏ、Ｎｉ、Ｎｂ、Ｍｏ）であるオリビン型複合酸化物粒子粉末において、レーザー回折式粒度分布測定装置の乾式分散ユニットを用いて測定した平均二次粒子径が０．０５μｍ〜５０μｍであり、、該オリビン型複合酸化物粒子粉末を１ｔ／ｃｍ２で加圧したときの圧縮密度が２．００ｇ／ｃｃ以上であり、平均二次粒子径（Ｄ５０）と走査型電子顕微鏡で観察した平均粒子径（ＤＳＥＭ）との比（Ｄ５０／ＤＳＥＭ）が０．８０〜１．２０であることを特徴とする非水電解質二次電池用オリビン型複合酸化物粒子粉末である（本発明１）。 That is, the present invention is a composition of Li x Fe 1-y M y PO 4 (0.8 <x <1.3,0 ≦ y <0.3, M: Mg, Zr, Mn, Al, Ti, Ce , Cr, Co, Ni, Nb, Mo), and the average secondary particle diameter measured using a dry dispersion unit of a laser diffraction particle size distribution analyzer is 0.05 μm to 50 μm. Yes, when the olivine-type composite oxide particle powder is pressed at 1 t / cm 2 , the compression density is 2.00 g / cc or more, and the average secondary particle diameter (D 50 ) and observed with a scanning electron microscope The olivine-type composite oxide particle powder for non-aqueous electrolyte secondary batteries, wherein the ratio (D 50 / D SEM ) to the average particle diameter (D SEM ) is 0.80 to 1.20 ( Invention 1).
また、本発明は、本発明１記載の非水電解質二次電池用オリビン型複合酸化物粒子粉末において、硫酸イオン含有量が１０００ｐｐｍ以下であってナトリウムイオン含有量が１０００ｐｐｍ以下であって、粒子内部及び／又は表面の炭素化合物の割合が０．２％以下ある非水電解質二次電池用オリビン型複合酸化物粒子粉末である（本発明２）。 Further, the present invention provides the olivine-type composite oxide particle powder for a non-aqueous electrolyte secondary battery according to the present invention 1, wherein the sulfate ion content is 1000 ppm or less and the sodium ion content is 1000 ppm or less, And / or olivine-type composite oxide particle powder for non-aqueous electrolyte secondary batteries having a surface carbon compound ratio of 0.2% or less (Invention 2).
また、本発明は、オリビン型構造を持つＬｉｘＦｅ１−ｙＭｙＰＯ４（０．９＜ｘ＜１．３、０≦ｙ＜０．３、Ｍ：Ｍｇ、Ｚｒ、Ｍｎ、Ａｌ、Ｔｉ、Ｃｅ、Ｃｒ、Ｃｏ、Ｎｉ、Ｎｂ、Ｍｏ）である複合酸化物の製造方法であって、鉄原料、リン原料、リチウム原料及び還元性を有する化合物を水溶液中で反応させた後、水洗・乾燥させ、還元性雰囲気下で３００〜７５０℃で熱処理することを特徴とする製造方法において、鉄原料として平均二次粒子径２μｍ以下である鉄系含水酸化物粒子粉末を用いることを特徴とする本発明１又は２記載のオリビン型複合酸化物の製造方法である（本発明３）。
The present invention also relates to Li x Fe 1- y My PO 4 (0.9 <x <1.3, 0 ≦ y <0.3, M: Mg, Zr, Mn, Al, having an olivine structure. Ti, Ce, Cr, Co, Ni, Nb, Mo), which is a method for producing a composite oxide, wherein an iron raw material, a phosphorus raw material, a lithium raw material, and a reducing compound are reacted in an aqueous solution, and then washed with water. In a production method characterized by drying and heat-treating at 300 to 750 ° C. in a reducing atmosphere, iron-based hydrous oxide particle powder having an average secondary particle diameter of 2 μm or less is used as an iron raw material. This is a method for producing the olivine-type composite oxide according to the first or second aspect of the present invention (Invention 3).
また、本発明は、本発明２記載の非水電解質二次電池用オリビン型複合酸化物の製造方法であって、Ｔａｖｏｒｉｔｅ型結晶構造から成る化合物から生成されることを特徴とする（本発明４）。 The present invention is also a method for producing an olivine type composite oxide for a non-aqueous electrolyte secondary battery according to the second aspect of the invention, wherein the olivine type composite oxide is produced from a compound having a Tavorite type crystal structure (Invention 4). ).
また、本発明は、本発明１〜３のいずれかに記載のオリビン型複合酸化物を正極活物質またはその一部として用いた非水電解液二次電池（本発明５）。 The present invention also provides a nonaqueous electrolyte secondary battery using the olivine-type composite oxide according to any one of the present inventions 1 to 3 as a positive electrode active material or a part thereof (the present invention 5).
本発明に係るオリビン型（ＬｉＦｅＰＯ４）複合酸化物粒子粉末は、残存硫酸イオン含有量が１０００ｐｐｍ以下かつ残存ナトリウムイオン含有量が１０００ｐｐｍ以下であるので、電極反応時のオリビン型ＬｉＦｅＰＯ４の構造が安定である。
また、本発明に係るオリビン型（ＬｉＦｅＰＯ４）複合酸化物粒子粉末は、平均二次粒子径が０．０５μｍ以上５０μｍ以下であり、１ｔ／ｃｍ２で加圧時の密度が２．００ｇ／ｃｃ以上であるので充填性が向上し、体積あたりの電池容量を向上させることができる。
従って、本発明に係るオリビン型（ＬｉＦｅＰＯ４）複合酸化物粒子粉末は、非水電解質二次電池用の正極活物質として好適である。
Since the olivine type (LiFePO 4 ) composite oxide particle powder according to the present invention has a residual sulfate ion content of 1000 ppm or less and a residual sodium ion content of 1000 ppm or less, the structure of the olivine type LiFePO 4 during the electrode reaction is stable. It is.
In addition, the olivine type (LiFePO 4 ) composite oxide particle powder according to the present invention has an average secondary particle size of 0.05 μm or more and 50 μm or less, and a density at pressurization at 1 t / cm 2 is 2.00 g / cc. Since it is above, a filling property improves and the battery capacity per volume can be improved.
Therefore, the olivine type (LiFePO 4 ) composite oxide particle powder according to the present invention is suitable as a positive electrode active material for a non-aqueous electrolyte secondary battery.
本発明の構成をより詳しく説明すれば次の通りである。 The configuration of the present invention will be described in more detail as follows.
先ず、本発明に係る非水電解質二次電池用オリビン型（ＬｉＦｅＰＯ４）複合酸化物粒子粉末について述べる。 First, the olivine type (LiFePO 4 ) composite oxide particle powder for a non-aqueous electrolyte secondary battery according to the present invention will be described.
本発明に係るオリビン型複合酸化物粒子粉末の組成は、ＬｉｘＦｅ１−ｙＭｙＰＯ４（０．８０＜ｘ＜１．３０、０≦ｙ＜０．３、Ｍ：Ｍｇ、Ｚｒ、Ｍｎ、Ａｌ、Ｔｉ、Ｃｅ、Ｃｒ、Ｃｏ、Ｎｉ、Ｎｂ、Ｍｏ）である。
ｘが前記範囲外の場合には、高い電池容量のＬｉＦｅＰＯ４複合酸化物を得ることができない。より好ましくは０．９０≦ｘ≦１．２０である。
ｙが前記範囲外の場合には、初期充放電容量の低下が著しくなる。より好ましくは０≦ｙ≦０．２５であり、更により好ましくは０≦ｙ≦０．２０である。
The composition of the olivine-type composite oxide particle powder according to the present invention is Li x Fe 1- y My PO 4 (0.80 <x <1.30, 0 ≦ y <0.3, M: Mg, Zr, Mn, Al, Ti, Ce, Cr, Co, Ni, Nb, Mo).
When x is out of the above range, a LiFePO 4 composite oxide having a high battery capacity cannot be obtained. More preferably, 0.90 ≦ x ≦ 1.20.
When y is outside the above range, the initial charge / discharge capacity is significantly reduced. More preferably, 0 ≦ y ≦ 0.25, and even more preferably 0 ≦ y ≦ 0.20.
本発明に係るオリビン型複合酸化物粒子粉末の平均二次粒子径は０．０５〜５０μｍである。平均二次粒子径が０．０５μｍ未満の場合には、充填密度の低下や電解液との反応性が増加するため好ましくない。５０μｍを超える場合には、工業的に生産することが困難となる。好ましい平均二次粒子径は０．５〜２０．０μｍである。 The average secondary particle diameter of the olivine-type composite oxide particle powder according to the present invention is 0.05 to 50 μm. When the average secondary particle diameter is less than 0.05 μm, the filling density is lowered and the reactivity with the electrolytic solution is increased. When it exceeds 50 μm, it is difficult to produce industrially. A preferable average secondary particle diameter is 0.5 to 20.0 μm.
本発明に係るオリビン型複合酸化物粒子粉末は、前記平均二次粒子径（Ｄ５０）と走査型電子顕微鏡で観察した平均粒子径（ＤＳＥＭ）との比（Ｄ５０／ＤＳＥＭ）が０．８０〜１．２０であることが好ましい。前記比が０．８未満の場合には、二次粒子（挙動粒子）が容易に解砕されてより小さな粒子となるため、解砕によって新たな界面が露出することになり、安定性が低下する。前記比が１．２を超える場合、挙動粒子同士が強く凝集したものであり、正極化する際に均一な分散を得ることが困難となる。
より好ましくは０．８５〜１．１５である。
In the olivine-type composite oxide particle powder according to the present invention, the ratio (D 50 / D SEM ) between the average secondary particle diameter (D 50 ) and the average particle diameter (D SEM ) observed with a scanning electron microscope is 0. It is preferable that it is .80-1.20. When the ratio is less than 0.8, secondary particles (behavior particles) are easily crushed into smaller particles, so that a new interface is exposed by pulverization, resulting in a decrease in stability. To do. When the ratio exceeds 1.2, the behaving particles are strongly aggregated, and it is difficult to obtain uniform dispersion when forming a positive electrode.
More preferably, it is 0.85-1.15.
本発明に係るオリビン型複合酸化物粒子粉末の粒子の粒子形状は、球状または扁平状（板状）であり鋭角部が少ないことが好ましい。 The particle shape of the olivine-type composite oxide particle powder according to the present invention is preferably spherical or flat (plate-like) and has few acute angle portions.
本発明に係るオリビン型複合酸化物粒子粉末の炭素含有量は０．２％以下であることが好ましい。炭素含有量が０．２％を超える場合、オリビン型複合酸化物を合成する際の熱処理において炭素含有量の制御が困難であるため、安定して合成することが困難である。また炭素含有量の増加と共に充填率が小さくなり、体積当たりの初期充放電容量が小さくなる。より好ましい炭素含有量は０．０１〜０．１０％である。 The carbon content of the olivine-type composite oxide particle powder according to the present invention is preferably 0.2% or less. When the carbon content exceeds 0.2%, it is difficult to stably synthesize because the carbon content is difficult to control in the heat treatment when synthesizing the olivine-type composite oxide. Further, as the carbon content increases, the filling rate decreases, and the initial charge / discharge capacity per volume decreases. A more preferable carbon content is 0.01 to 0.10%.
本発明に係るオリビン型複合酸化物粒子粉末のＢＥＴ比表面積は１．０〜２５ｍ２／ｇが好ましい。ＢＥＴ比表面積値が１ｍ２／ｇ未満の場合には、充放電レートが低下する。２５ｍ２／ｇを超える場合には充填密度の低下や電解液との反応性が増加するため好ましくない。より好ましいＢＥＴ比表面積は２．０〜２０ｍ２／ｇである。 The BET specific surface area of the olivine-type composite oxide particle powder according to the present invention is preferably 1.0 to 25 m 2 / g. When the BET specific surface area value is less than 1 m 2 / g, the charge / discharge rate decreases. If it exceeds 25 m 2 / g, the filling density is lowered and the reactivity with the electrolytic solution is increased. A more preferable BET specific surface area is 2.0 to 20 m 2 / g.
本発明に係るオリビン型複合酸化物粒子粉末の１ｔ／ｃｍ２で加圧したときの圧縮密度は、２．００ｇ／ｃｃ以上であることが好ましい。圧縮密度が２．００ｇ／ｃｃ未満の場合、体積あたりの電池容量が少なくなる。より好ましくは２．１０ｇ／ｃｃ以上であり、真密度に近づけば近づくほど良い。本発明に係るオリビン型複合酸化物は一次粒子が密に集合した構造を取っているので、圧縮密度が高いと考えられる。 The compression density when the olivine-type composite oxide particle powder according to the present invention is pressurized at 1 t / cm 2 is preferably 2.00 g / cc or more. When the compression density is less than 2.00 g / cc, the battery capacity per volume decreases. More preferably, it is 2.10 g / cc or more, and the closer to the true density, the better. Since the olivine-type complex oxide according to the present invention has a structure in which primary particles are densely assembled, it is considered that the compression density is high.
次に、本発明に係るオリビン型複合酸化物粒子粉末の製造法について述べる。 Next, the manufacturing method of the olivine type complex oxide particle powder according to the present invention will be described.
本発明に係るオリビン型複合酸化物粒子粉末は、鉄系含水酸化物、還元性を有する化合物、溶解したリン酸及びリチウム化合物溶液を湿式法により反応させ、得られた粉末を非酸化性または還元性条件下で焼成して得ることができる。 The olivine-type composite oxide particle powder according to the present invention is obtained by reacting an iron-based hydrous oxide, a reducing compound, a dissolved phosphoric acid and a lithium compound solution by a wet method, and the resulting powder is non-oxidizing or reducing It can be obtained by baking under sexual conditions.
本発明においては鉄原料として用いる鉄系含水酸化物粒子粉末は、ＢＥＴ比表面積が３０〜４００ｍ２／ｇであって平均二次粒子径が２μｍ以下である鉄系含水酸化物粒子粉末を用いることができる。 In the present invention, the iron-based hydrous oxide particle powder used as the iron raw material is an iron-based hydrous oxide particle powder having a BET specific surface area of 30 to 400 m 2 / g and an average secondary particle diameter of 2 μm or less. Can do.
本発明において鉄系含水酸化物粒子粉末としては、ゲータイト（α−ＦｅＯＯＨ）が好ましく、Ｍｇ、Ｚｒ、Ｍｎ、Ａｌ、Ｔｉ、Ｃｅ、Ｃｒ、Ｃｏ、Ｎｉ、Ｎｂ又はＭｏ等の異種金属を含有しても良い。 In the present invention, the iron-based hydrous oxide particle powder is preferably goethite (α-FeOOH), and contains different metals such as Mg, Zr, Mn, Al, Ti, Ce, Cr, Co, Ni, Nb or Mo. May be.
本発明において鉄系含水酸化物粒子粉末の平均二次粒子径は２．０μｍ以下が好ましい。平均二次粒子径が２．０μｍを超える場合、Ｔａｖｏｒｉｔｅ型結晶構造からなる化合物への反応が遅く、未反応の鉄系含水酸化物粒子が残存する。より好ましい平均二次粒子径は０．３〜１．８μｍである。 In the present invention, the average secondary particle diameter of the iron-containing hydrous oxide particle powder is preferably 2.0 μm or less. When the average secondary particle diameter exceeds 2.0 μm, the reaction to the compound having a Tavorite type crystal structure is slow, and unreacted iron-containing hydrated oxide particles remain. A more preferable average secondary particle diameter is 0.3 to 1.8 μm.
本発明において鉄系含水酸化物粒子粉末のＢＥＴ比表面積は３０〜４００ｍ２／ｇが好ましい。ＢＥＴ比表面積が前記範囲外の場合、Ｔａｖｏｒｉｔｅ型結晶構造からなる化合物への反応が遅く、未反応の鉄系含水酸化物粒子が残存する。より好ましくは４０〜２００ｍ２／ｇである。 In the present invention, the BET specific surface area of the iron-containing hydrated oxide particle powder is preferably 30 to 400 m 2 / g. When the BET specific surface area is out of the above range, the reaction to the compound having a Tavorite type crystal structure is slow, and unreacted iron-based hydrous oxide particles remain. More preferably, it is 40-200 m < 2 > / g.
本発明においては鉄原料として残存硫酸イオン含有量が１０００ｐｐｍ以下かつ残存ナトリウムイオン含有量が１０００ｐｐｍ以下である鉄系水酸化物を用いることができる。 In the present invention, an iron hydroxide having a residual sulfate ion content of 1000 ppm or less and a residual sodium ion content of 1000 ppm or less can be used as the iron raw material.
鉄系含水酸化物は、ヘンシェルミキサー、らいかい機、ハイスピードミキサー、万能攪拌機、ボールミル等の乾式および湿式混合機を用いてほぐし、還元性を有する化合物、リン原料及びリチウム原料を含む水溶液と混合する。 Iron-based hydrous oxides are loosened using dry and wet mixers such as Henschel mixers, rakai machines, high speed mixers, universal stirrers, and ball mills, and mixed with aqueous solutions containing reducing compounds, phosphorus materials, and lithium materials. To do.
混合後、５０〜１６０℃の温度範囲で水溶液中で反応させ、Ｔａｖｏｒｉｔｅ型結晶構造からなる化合物を合成する。より好ましくは５０〜１００℃である。反応時間は０．５〜７２時間が好ましい。 After mixing, the reaction is carried out in an aqueous solution at a temperature range of 50 to 160 ° C. to synthesize a compound having a Tavorite type crystal structure. More preferably, it is 50-100 degreeC. The reaction time is preferably 0.5 to 72 hours.
反応終了後、通風式乾燥機、凍結真空乾燥機、スプレー乾燥機、フィルタープレス、バキュームフィルター、フィルターシックナー等を用いて余分な水分を除去することができる。 After completion of the reaction, excess water can be removed using a ventilating dryer, freeze vacuum dryer, spray dryer, filter press, vacuum filter, filter thickener or the like.
リン酸塩およびリチウム塩の添加量は、鉄系含水酸化物に含まれる鉄イオンと異種金属イオンの総和に対して、それぞれモルパーセント換算で９５〜１０５、９０〜１２０の範囲が好ましい。
リン原料であるリン酸塩としては、オルトリン酸、五酸化リン等が使用できる。リチウム塩としては、炭酸リチウム、水酸化リチウム等が使用できる。またリン酸２水素リチウム、リン酸水素アンモニウム等も使用できる。
リン酸およびリチウム塩溶液に共存させることができる還元性を有する化合物としては、ショ糖、クエン酸、アスコルビン酸、デキストリン、でんぷん、マンナン、トレハロース等が挙げられる。
The addition amount of phosphate and lithium salt is preferably in the range of 95 to 105 and 90 to 120 in terms of mole percent, respectively, with respect to the sum of iron ions and different metal ions contained in the iron-based hydrous oxide.
As the phosphate as the phosphorus raw material, orthophosphoric acid, phosphorus pentoxide and the like can be used. As the lithium salt, lithium carbonate, lithium hydroxide or the like can be used. Further, lithium dihydrogen phosphate, ammonium hydrogen phosphate and the like can be used.
Examples of compounds having reducibility that can coexist in phosphoric acid and lithium salt solutions include sucrose, citric acid, ascorbic acid, dextrin, starch, mannan, trehalose and the like.
中間生成物であるＴａｖｏｒｉｔｅ型結晶構造からなる化合物を、走査型電子顕微鏡観察した平均粒子径（ＤＳＥＭ）、は０．０５〜５０μｍ、ＢＥＴ比表面積が０．１〜１５．０ｍ２／ｇであることが好ましい。 The average particle diameter (D SEM ) of a compound having a Tavorite type crystal structure as an intermediate product observed with a scanning electron microscope is 0.05 to 50 μm, and the BET specific surface area is 0.1 to 15.0 m 2 / g. Preferably there is.
Ｔａｖｏｒｉｔｅ型結晶構造からなる化合物は、ガス流通式箱型マッフル炉、ガス流通式回転炉、流動熱処理炉等で熱処理することができる。 A compound having a Tavorite type crystal structure can be heat-treated in a gas flow type box muffle furnace, a gas flow type rotary furnace, a fluidized heat treatment furnace or the like.
加熱焼成温度は、３００℃〜７５０℃が好ましい。３００℃未満の場合には鉄イオンの還元反応が十分に進まず、オリビン型（ＬｉＦｅＰＯ４）複合酸化物以外の結晶相が残存し、７５０℃を超える場合には別の結晶相が出現するので好ましくない。焼成時の雰囲気は還元ガス雰囲気が好ましい。焼成時間は１〜２０時間が好ましい。 The baking temperature is preferably 300 ° C to 750 ° C. When the temperature is lower than 300 ° C., the reduction reaction of iron ions does not proceed sufficiently, and a crystal phase other than the olivine type (LiFePO 4 ) composite oxide remains, and when it exceeds 750 ° C., another crystal phase appears. It is not preferable. The atmosphere during firing is preferably a reducing gas atmosphere. The firing time is preferably 1 to 20 hours.
次に、本発明に係るオリビン型（ＬｉＦｅＰＯ４）複合酸化物粒子粉末からなる正極活物質を用いた正極について述べる。 Next, a positive electrode using a positive electrode active material made of olivine type (LiFePO 4 ) composite oxide particles according to the present invention will be described.
本発明に係るオリビン型複合酸化物粒子粉末を用いて正極を製造する場合には、常法に従って、導電剤と結着剤とを添加混合する。導電剤としてはアセチレンブラック、カーボンブラック、黒鉛等が好ましく、結着剤としてはポリテトラフルオロエチレン、ポリフッ化ビニリデン等が好ましい。 When a positive electrode is produced using the olivine-type composite oxide particle powder according to the present invention, a conductive agent and a binder are added and mixed according to a conventional method. As the conductive agent, acetylene black, carbon black, graphite and the like are preferable, and as the binder, polytetrafluoroethylene, polyvinylidene fluoride and the like are preferable.
本発明に係るオリビン型複合酸化物粒子粉末を用いて製造される二次電池は、前記正極、負極及び電解質から構成される。 The secondary battery manufactured using the olivine-type composite oxide particle powder according to the present invention includes the positive electrode, the negative electrode, and the electrolyte.
負極活物質としては、リチウム金属、リチウム／アルミニウム合金、リチウム／スズ合金、グラファイトや黒鉛等を用いることができる。 As the negative electrode active material, lithium metal, lithium / aluminum alloy, lithium / tin alloy, graphite, graphite, or the like can be used.
また、電解液の溶媒としては、炭酸エチレンと炭酸ジエチルの組み合わせ以外に、炭酸プロピレン、炭酸ジメチル等のカーボネート類や、ジメトキシエタン等のエーテル類の少なくとも１種類を含む有機溶媒を用いることができる。 In addition to the combination of ethylene carbonate and diethyl carbonate, an organic solvent containing at least one of carbonates such as propylene carbonate and dimethyl carbonate and ethers such as dimethoxyethane can be used as the solvent for the electrolytic solution.
さらに、電解質としては、六フッ化リン酸リチウム以外に、過塩素酸リチウム、四フッ化ホウ酸リチウム等のリチウム塩の少なくとも１種類を上記溶媒に溶解して用いることができる。 Further, as the electrolyte, in addition to lithium hexafluorophosphate, at least one lithium salt such as lithium perchlorate and lithium tetrafluoroborate can be dissolved in the above solvent and used.
本発明に係るオリビン型複合酸化物粒子粉末を用いて製造した二次電池は、Ｃ／２０の充放電レートで、初期放電容量が１３０〜１４５ｍＡｈ／ｇ、５Ｃの充放電レートで、初期放電容量が６０〜９０ｍＡｈ／ｇ程度である。 The secondary battery manufactured using the olivine-type composite oxide particle powder according to the present invention has a C / 20 charge / discharge rate, an initial discharge capacity of 130 to 145 mAh / g, a charge / discharge rate of 5C, and an initial discharge capacity. Is about 60 to 90 mAh / g.
＜作用＞
本発明に係るオリビン型（ＬｉＦｅＰＯ４）複合酸化物粒子粉末が前記特性を有するのは、残存硫酸イオン含有量が１０００ｐｐｍ以下かつナトリウムイオン１０００ｐｐｍ以下であり、平均二次粒子径が０．０５〜５０μｍ、形状が球状または扁平状であるため、高充填性であり、該オリビン型複合酸化物粒子粉末を正極活物質として用いた二次電池は、高充放電特性及び高いレート特性を有すると本発明者は推定している。
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The olivine-type (LiFePO 4 ) composite oxide particle powder according to the present invention has the above-mentioned properties because the residual sulfate ion content is 1000 ppm or less and sodium ion is 1000 ppm or less, and the average secondary particle size is 0.05 to 50 μm. The secondary battery using the olivine-type composite oxide particle powder as a positive electrode active material has a high charge / discharge characteristic and a high rate characteristic. Estimate.
また、本発明に係るオリビン型複合酸化物粒子粉末は、走査型電子顕微鏡で観察した平均二次粒子径と乾式法によるレーザー回折装置で測定した平均二次粒子径とがほぼ同程度であるので、挙動粒子の大きさを維持することができ、正極を作製する際に、解砕されて新たな界面が露出することもないため、安定性に優れた二次電池を製造することができる。 Further, the olivine-type composite oxide particle powder according to the present invention has an average secondary particle diameter observed with a scanning electron microscope and an average secondary particle diameter measured with a laser diffraction apparatus by a dry method are approximately the same. The size of the behavior particles can be maintained, and when the positive electrode is produced, it is not crushed and a new interface is not exposed, so that a secondary battery having excellent stability can be produced.
また、本発明においては、中間生成物であるＴａｖｏｒｉｔｅ型結晶構造の化合物の平均二次粒子径とオリビン型複合酸化物粒子粉末の平均二次粒子径とがほぼ同程度であるので、粒子径の制御の点で、容易に製造することができる。 Further, in the present invention, the average secondary particle size of the compound of the Tavorite type crystal structure which is an intermediate product and the average secondary particle size of the olivine type composite oxide particle powder are approximately the same, In terms of control, it can be easily manufactured.
本発明の代表的な実施の形態は次の通りである。 A typical embodiment of the present invention is as follows.
各粒子粉末の平均二次粒子径（Ｄ５０）は「レーザー回折式粒度分布測定装置 ｍｏｄｅｌ ＨＥＬＯＳ ＬＡ／ＫＡ」（ＳＹＭＰＡＴＥＣ社製）の乾式分散ユニットを用いて、分散圧０．５ＭＰａ（５ｂａｒ）にて測定して求めた。 The average secondary particle size (D 50 ) of each particle powder was adjusted to a dispersion pressure of 0.5 MPa (5 bar) using a dry dispersion unit of “Laser diffraction particle size distribution measuring device model HELOS LA / KA” (manufactured by SYMPATEC). And measured.
粒子形状は日立製Ｓ−４８００型 走査型電子顕微鏡を用いて観察した。走査型電子顕微鏡で観察した平均二次粒子径（ＤＳＥＭ）は、前記走査型電子顕微鏡を用いて測定した３００個の粒子の個数平均粒子径である。 The particle shape was observed using a Hitachi S-4800 scanning electron microscope. The average secondary particle diameter ( DSEM ) observed with a scanning electron microscope is the number average particle diameter of 300 particles measured using the scanning electron microscope.
比表面積は試料を窒素ガス下で１２０℃、４５分間乾燥脱気した後、ＭＯＮＯＳＯＲＢ［ユアサアイオニックス（株）製］を用いてＢＥＴ１点連続法により求めた比表面積である。 The specific surface area is a specific surface area determined by the BET one-point continuous method using MONOSORB [manufactured by Yuasa Ionics Co., Ltd.] after drying and deaeration of the sample under nitrogen gas at 120 ° C. for 45 minutes.
加圧時の密度は１ｔ／ｃｍ２の圧力を掛けたときの密度である。 The density at the time of pressurization is a density when a pressure of 1 t / cm 2 is applied.
硫酸イオン量は試料を炭素、硫黄測定装置ＥＭＩＡ−８２０［（株）ホリバ製作所製］を用いて試料を燃焼炉で酸素気流中にて燃焼させ、測定された硫黄分の量から換算した硫酸イオン量である。 The amount of sulfate ion was determined by burning the sample with carbon and sulfur measuring device EMIA-820 [manufactured by Horiba Ltd.] in a combustion furnace in an oxygen stream and converting the measured sulfur content. Amount.
異種金属元素、残存ナトリウムイオン量は、発光プラズマ分析装置ＩＣＡＰ−６５００［サーモフィッシャーサイエンティフィク社製］を用いて測定した。 The amount of different metal elements and residual sodium ions were measured using an emission plasma analyzer ICAP-6500 [manufactured by Thermo Fisher Scientific Co.].
粒子の結晶構造は「理学電機製 Ｘ線回折装置ＲＩＮＴ２５００」を用い、Ｃｕ−Ｋα、４０ｋＶ，３００ｍＡにより測定した。 The crystal structure of the particles was measured with Cu-Kα, 40 kV, 300 mA using “X-ray diffractometer RINT2500 manufactured by Rigaku Corporation”.
オリビン型複合酸化物を用いてコインセルによる初期充放電特性及び高温保存特性評価を行った。
まず、正極活物質としてオリビン型複合酸化物を９０重量％、導電材としてアセチレンブラックを３重量％及びグラファイトＫＳ−１６を３重量％、バインダーとしてＮ−メチルピロリドンに溶解したポリフッ化ビニリデン４重量％とを混合した後、Ａｌ金属箔に塗布し１５０℃にて乾燥した。このシートを１６ｍｍφに打ち抜いた後、５ｔ／ｃｍ２で圧着し、電極厚みを５０μｍとした物を正極に用いた。負極は１６ｍｍφに打ち抜いた金属リチウムとし、電解液は１ｍｏｌ／ｌのＬｉＰＦ６を溶解したＥＣとＤＭＣを体積比１：２で混合した溶液を用いてＣＲ２０３２型コインセルを作成した。
初期充放電特性は、室温で充電は４．５Ｖまで０．２ｍＡ／ｃｍ２にて行った後、放電を２．０Ｖまで０．２ｍＡ／ｃｍ２にて行い、その時の初期充電容量、初期放電容量及び初期効率を測定した。
The initial charge / discharge characteristics and high-temperature storage characteristics of the coin cell were evaluated using olivine type complex oxide.
First, 90% by weight of olivine type composite oxide as a positive electrode active material, 3% by weight of acetylene black as a conductive material and 3% by weight of graphite KS-16, 4% by weight of polyvinylidene fluoride dissolved in N-methylpyrrolidone as a binder And then applied to an Al metal foil and dried at 150 ° C. This sheet was punched to 16 mmφ, and then pressure-bonded at 5 t / cm 2 , and an electrode having a thickness of 50 μm was used for the positive electrode. A CR2032-type coin cell was prepared by using metallic lithium punched to 16 mmφ as a negative electrode and a solution obtained by mixing EC and DMC in which 1 mol / l LiPF 6 was dissolved in a volume ratio of 1: 2 as an electrolytic solution.
The initial charge / discharge characteristics are as follows: at room temperature, the charge is performed at 0.2 mA / cm 2 up to 4.5 V, and then the discharge is performed at 0.2 mA / cm 2 up to 2.0 V. The initial charge capacity and initial discharge at that time Capacity and initial efficiency were measured.
＜実施例１＞
水酸化リチウム２５７ｇをイオン交換水１８６２ｇに溶かし、その溶液をオルトリン酸６８２ｇにゆっくり投入し、混合溶液を得た。
一方、ＢＥＴ比表面積が６２．８ｍ２／ｇのゲータイト粒子粉末５８８ｇとイオン交換水１３７２ｇを、ジルコニアボールを用いて１時間ボールミル処理し、ゲータイト粒子のスラリーを得た。スラリーの一部を抜き取って乾燥して、平均二次粒子径（Ｄ５０）を測定したところ、平均二次粒子径（Ｄ５０）は１．３８μｍであった。
次に、このスラリーを加熱式混合攪拌機に入れ、攪拌しながら水酸化リチウムとオルトリン酸の混合溶液及び６７ｇのショ糖を投入し、容積が２０Ｌとなるようイオン交換水で混合スラリーの量を調整した。その後ゆっくり攪拌しながら９５℃に加熱し、混合攪拌機内の温度を９５℃に保持させた状態で２０時間反応させた。反応後、取り出したスラリーを、プレスフィルターを用いて５倍量の水で水洗を行った後、１４時間通風式乾燥機で乾燥処理を行い、反応乾燥粉末１０４９ｇを得た。
得られた反応粉末を走査型顕微鏡で観察した結果、平均二次粒子径（ＤＳＥＭ）は１０．８μｍであり、ＢＥＴ比表面積は０．９ｍ２／ｇであり、粒子形状は球状形であることがわかった。またＸ線回折測定の結果、反応粉末は、Ｔａｖｏｒｉｔｅ型結晶構造であることがわかった。
<Example 1>
257 g of lithium hydroxide was dissolved in 1862 g of ion-exchanged water, and the solution was slowly added to 682 g of orthophosphoric acid to obtain a mixed solution.
On the other hand, 588 g of goethite particle powder having a BET specific surface area of 62.8 m 2 / g and 1372 g of ion-exchanged water were ball-milled for 1 hour using zirconia balls to obtain a goethite particle slurry. A part of the slurry was extracted and dried, and the average secondary particle diameter (D 50 ) was measured. The average secondary particle diameter (D 50 ) was 1.38 μm.
Next, this slurry is put into a heating type mixing stirrer, and a mixed solution of lithium hydroxide and orthophosphoric acid and 67 g of sucrose are added while stirring, and the amount of the mixed slurry is adjusted with ion-exchanged water so that the volume becomes 20 L. did. Thereafter, the mixture was heated to 95 ° C. with slow stirring, and reacted for 20 hours while maintaining the temperature in the mixing stirrer at 95 ° C. After the reaction, the slurry taken out was washed with 5 times the amount of water using a press filter, and then dried with a ventilated dryer for 14 hours to obtain 1049 g of a reaction dry powder.
As a result of observing the obtained reaction powder with a scanning microscope, the average secondary particle diameter (D SEM ) was 10.8 μm, the BET specific surface area was 0.9 m 2 / g, and the particle shape was spherical. I understood it. As a result of X-ray diffraction measurement, the reaction powder was found to have a Tavorite type crystal structure.
得られたＴａｖｏｒｉｔｅ型結晶構造の化合物のＳＥＭ写真を図１に示す。 FIG. 1 shows an SEM photograph of the obtained compound having a Tavorite crystal structure.
この混合物を水素ガス雰囲気下、５５０℃にて３時間焼成し、解砕した。
得られた焼成物の炭素含有量は０．０１３ｗｔ％、硫酸イオン（ＳＯ４）含有量は２６０ｐｐｍ、ナトリウム含有量は２２０ｐｐｍであり、走査型顕微鏡で観察した平均二次粒子径（ＤＳＥＭ）は１０．５０μｍ、ＢＥＴ比表面積は３．８ｍ２／ｇ、粒子形状は球状形、圧縮密度は２．３８ｇ／ｃｃであった。またＸ線回折測定の結果、オリビン型結晶構造であることがわかった。得られたオリビン型複合酸化物粒子粉末の電子顕微鏡写真を図２に示す。「ＪＥＯＬ ＨＥＬＯＳ ＳＹＳＴＥＭ ｐａｒｔｉｃｌｅ ｓｉｚｅ ａｎａｌｙｚｅｒ」で測定した平均二次粒子径Ｄ５０は１０．６０μｍであり、ＳＥＭ写真の平均二次粒子径とほぼ一致していることが確認でき、Ｄ５０／ＤＳＥＭ＝１．０１であった。
ここで、ＢＥＴ比表面積が熱処理後に増加していることについて、Ｔａｖｏｒｉｔｅ型結晶構造であるＬｉＦｅＰＯ４（ＯＨ）はＬｉＦｅＰＯ４化する際に還元雰囲気中での熱処理によりＯＨが抜け出てしまい、空孔が形成されてしまう為だと考えている。そのため、Ｔａｖｏｒｉｔｅ型結晶構造の化合物の粒子形状を残したまま空孔が存在するオリビン型結晶構造が形成され、平均粒子径が大きくても高い充放電特性を有していると考えている。
This mixture was fired at 550 ° C. for 3 hours in a hydrogen gas atmosphere and crushed.
Carbon content 0.013% of the obtained baked product, the sulfate ion (SO 4) content 260 ppm, the sodium content is 220 ppm, an average secondary particle diameter was observed with a scanning microscope (D SEM) is It was 10.50 μm, the BET specific surface area was 3.8 m 2 / g, the particle shape was spherical, and the compression density was 2.38 g / cc. Further, as a result of X-ray diffraction measurement, it was found to be an olivine type crystal structure. An electron micrograph of the obtained olivine-type composite oxide particle powder is shown in FIG. The average secondary particle diameter D 50 measured by “JEOL HELOS SYSTEM particle size analyzer” is 10.60 μm, and it can be confirmed that the average secondary particle diameter of the SEM photograph is almost equal to D 50 / D SEM = 1.01.
Here, regarding the fact that the BET specific surface area is increased after the heat treatment, LiFePO 4 (OH), which is a Tavorite type crystal structure, is converted into LiFePO 4 , so that OH escapes by heat treatment in a reducing atmosphere, and vacancies are generated. I think it is because it is formed. Therefore, it is considered that an olivine-type crystal structure in which pores exist with the particle shape of the compound having a Tavorite-type crystal structure remaining is formed, and that it has high charge / discharge characteristics even if the average particle size is large.
＜実施例２＞
９５℃の混合スラリーに３７ｇのステアリン酸を加えた以外は実施例１と同様に行った。尚、ゲータイト粒子粉末を、ジルコニアボールを用いて１時間ボールミル処理して、ゲータイト粒子のスラリーを得た。このときのゲータイト粒子粉末の平均二次粒子径（Ｄ５０）は１．３５μｍであった。
得られた反応粉末を走査型顕微鏡で観察した結果、反応粉末の平均二次粒子径（ＤＳＥＭ）は３．０μｍであり、ＢＥＴ比表面積は１．５ｍ２／ｇであり、粒子形状は扁平形であることがわかった。またＸ線回折測定の結果、粉末は、Ｔａｖｏｒｉｔｅ型結晶構造であることがわかった。得られたＴａｖｏｒｉｔｅ型結晶構造の化合物のＳＥＭ写真を図３に示す。
この混合物を水素ガス雰囲気下、５５０℃にて３時間焼成し、解砕した。
得られた焼成物の炭素含有量０．０４６ｗｔ％、硫酸イオン（ＳＯ４）含有量は２３０ｐｐｍ、ナトリウム含有量は２００ｐｐｍであり、走査型顕微鏡で観察した結果、平均二次粒子径（ＤＳＥＭ）は３．０３μｍ、ＢＥＴ比表面積は５．８ｍ２／ｇ、粒子形状は扁平形（板状）であり、圧縮密度は２．３７ｇ／ｃｃであった。またＸ線回折測定の結果、オリビン型結晶構造であることがわかった。得られたオリビン型複合酸化物粒子粉末の電子顕微鏡写真を図４に示す。「ＪＥＯＬ ＨＥＬＯＳ ＳＹＳＴＥＭ ｐａｒｔｉｃｌｅ ｓｉｚｅ ａｎａｌｙｚｅｒ」で測定した平均二次粒子径Ｄ５０は３．１１μｍであり、ＳＥＭ写真の平均二次粒子径とほぼ一致していることが確認でき、Ｄ５０／ＤＳＥＭ＝１．０３であった。
<Example 2>
The same procedure as in Example 1 was performed except that 37 g of stearic acid was added to the 95 ° C. mixed slurry. The goethite particles were ball milled for 1 hour using zirconia balls to obtain goethite particle slurry. The average secondary particle size (D 50 ) of the goethite particles at this time was 1.35 μm.
As a result of observing the obtained reaction powder with a scanning microscope, the average secondary particle diameter (D SEM ) of the reaction powder was 3.0 μm, the BET specific surface area was 1.5 m 2 / g, and the particle shape was flat. It turned out to be a shape. As a result of X-ray diffraction measurement, it was found that the powder had a Tavorite type crystal structure. FIG. 3 shows an SEM photograph of the obtained compound having a Tavorite crystal structure.
This mixture was fired at 550 ° C. for 3 hours in a hydrogen gas atmosphere and crushed.
The obtained fired product has a carbon content of 0.046 wt%, a sulfate ion (SO 4 ) content of 230 ppm, and a sodium content of 200 ppm. As a result of observation with a scanning microscope, the average secondary particle size ( DSEM ) Was 3.03 μm, the BET specific surface area was 5.8 m 2 / g, the particle shape was flat (plate), and the compression density was 2.37 g / cc. Further, as a result of X-ray diffraction measurement, it was found to be an olivine type crystal structure. An electron micrograph of the obtained olivine-type composite oxide particle powder is shown in FIG. The average secondary particle diameter D 50 measured by “JEOL HELOS SYSTEM particle size analyzer” is 3.11 μm, and it can be confirmed that the average secondary particle diameter of the SEM photograph is almost the same, and D 50 / D SEM = 1.03.
＜実施例３＞
水酸化リチウム４２８ｇをイオン交換水３１０２ｇに溶かし、その溶液をオルトリン酸１１３７ｇにゆっくり投入し、混合溶液を得た。
一方、ゲータイト粒子粉末９８０ｇとイオン交換水２２８７ｇを、ジルコニアボールを用いて１時間ボールミル処理しゲータイト粒子のスラリーを得た。このときのゲータイト粒子粉末の平均二次粒子径Ｄ５０は１．３２μｍであった。
次に、このスラリーを加熱式混合攪拌機に入れ、攪拌しながら前記混合溶液と１９ｇのショ糖を投入し、容積が２０Ｌとなるようイオン交換水で混合スラリーの量を調整した。その後、ゆっくり攪拌しながら９５℃に加熱し、混合攪拌機内の温度を９５℃に保持させた状態で４０時間反応させた。反応後、取り出したスラリーを、プレスフィルターを用いて５倍量の水で水洗を行った後、１４時間通風式乾燥機で乾燥処理を行い、反応乾燥粉末１７４８ｇを得た。
得られた反応粉末を走査型顕微鏡で観察した結果、反応粉末の平均二次粒子径（ＤＳＥＭ）は５．２μｍであり、ＢＥＴ比表面積は１．１ｍ２／ｇであり、粒子形状は球状形であることがわかった。また、Ｘ線回折測定の結果、粉末は、Ｔａｖｏｒｉｔｅ型結晶構造であることがわかった。
この混合物を水素ガス雰囲気下、５５０℃にて３時間焼成し、解砕した。得られた焼成物の炭素含有量は０．０１９ｗｔ％、硫酸イオン（ＳＯ４）含有量は２１０ｐｐｍ、ナトリウム含有量は１８０ｐｐｍであり、走査型顕微鏡で観察した結果、平均二次粒子径（ＤＳＥＭ）は５．０６μｍ、ＢＥＴ比表面積は４．７ｍ２／ｇ、粒子形状は球状形、圧縮密度は２．１２ｇ／ｃｃであった。またＸ線回折測定の結果、オリビン型結晶構造であることがわかった。「ＪＥＯＬ ＨＥＬＯＳ ＳＹＳＴＥＭ ｐａｒｔｉｃｌｅ ｓｉｚｅ ａｎａｌｙｚｅｒ」で測定した平均二次粒子径Ｄ５０は４．９５μｍであり、ＳＥＭ写真の平均二次粒子径とほぼ一致していることが確認でき、Ｄ５０／ＤＳＥＭ＝０．９８であった。
<Example 3>
Lithium hydroxide (428 g) was dissolved in ion-exchanged water (3102 g), and the solution was slowly added to orthophosphoric acid (1137 g) to obtain a mixed solution.
On the other hand, 980 g of goethite particle powder and 2287 g of ion-exchanged water were ball milled for 1 hour using zirconia balls to obtain a slurry of goethite particles. The average secondary particle diameter D 50 of the goethite particles at this time was 1.32 .mu.m.
Next, the slurry was put into a heating type mixing stirrer, and the mixed solution and 19 g of sucrose were added while stirring, and the amount of the mixed slurry was adjusted with ion-exchanged water so that the volume became 20 L. Then, it heated at 95 degreeC, stirring slowly, and was made to react for 40 hours, with the temperature in a mixing stirrer kept at 95 degreeC. After the reaction, the slurry taken out was washed with 5 times the amount of water using a press filter and then dried with a ventilating dryer for 14 hours to obtain 1748 g of a reaction dry powder.
As a result of observing the obtained reaction powder with a scanning microscope, the average secondary particle diameter (D SEM ) of the reaction powder was 5.2 μm, the BET specific surface area was 1.1 m 2 / g, and the particle shape was spherical. It turned out to be a shape. As a result of X-ray diffraction measurement, it was found that the powder had a Tavorite type crystal structure.
This mixture was fired at 550 ° C. for 3 hours in a hydrogen gas atmosphere and crushed. The obtained fired product had a carbon content of 0.019 wt%, a sulfate ion (SO 4 ) content of 210 ppm, and a sodium content of 180 ppm. As a result of observation with a scanning microscope, the average secondary particle size ( DSEM ) Was 5.06 μm, the BET specific surface area was 4.7 m 2 / g, the particle shape was spherical, and the compression density was 2.12 g / cc. Further, as a result of X-ray diffraction measurement, it was found to be an olivine type crystal structure. The average secondary particle diameter D 50 measured by “JEOL HELOS SYSTEM particle size analyzer” is 4.95 μm, and it can be confirmed that the average secondary particle diameter of the SEM photograph is almost the same, and D 50 / D SEM = 0.98.
＜実施例４＞
水酸化リチウム６８５ｇをイオン交換水４９６４ｇに溶かし、その溶液をオルトリン酸１８２０ｇにゆっくり投入し、混合溶液を得た。
一方、ゲータイト粒子粉末１５６８ｇとイオン交換水３６５９ｇを、ジルコニアボールを用いて１時間ボールミル処理して、ゲータイト粒子のスラリーを得た。このときのゲータイト粒子粉末の平均二次粒子径Ｄ５０は１．４０μｍであった。
次に、このスラリーを加熱式混合攪拌機に入れ、攪拌しながら前記混合溶液と９３ｇのアスコルビン酸を投入し、容積が２０Ｌとなるようイオン交換水で混合スラリーの量を調整した。その後ゆっくり攪拌しながら９５℃に加熱し、混合攪拌機内の温度を９５℃に保持させた状態で５時間反応させた。反応後、取り出したスラリー液を、プレスフィルターを用いて５倍量の水で水洗を行った後、１４時間通風式乾燥機で乾燥処理を行い、反応乾燥粉末２７９６ｇを得た。
得られた乾燥粉末について走査型顕微鏡で観察した結果、反応粉末の平均二次粒子径（ＤＳＥＭ）は１．８μｍであり、ＢＥＴ比表面積は１．６ｍ２／ｇであり、粒子形状は球状形であることがわかった。またＸ線回折測定の結果、粉末は、Ｔａｖｏｒｉｔｅ型結晶構造であることがわかった。
この混合物を水素ガス雰囲気下、５５０℃にて３時間焼成し、解砕した。
得られた焼成物の炭素含有量は０．０２２ｗｔ％、硫酸イオン（ＳＯ４）含有量は２００ｐｐｍ、ナトリウム含有量は１６０ｐｐｍであり、走査型顕微鏡で観察した結果、平均二次粒子径（ＤＳＥＭ）は１．９２μｍ、ＢＥＴ比表面積は６．０ｍ２／ｇ、粒子形状は球状形、圧縮密度は２．２０ｇ／ｃｃであった。またＸ線回折測定の結果、オリビン型結晶構造であることがわかった。「ＪＥＯＬ ＨＥＬＯＳ ＳＹＳＴＥＭ ｐａｒｔｉｃｌｅ ｓｉｚｅ ａｎａｌｙｚｅｒ」で測定した平均二次粒子径Ｄ５０は１．７６μｍであり、ＳＥＭ写真の平均二次粒子径とほぼ一致していることが確認でき、Ｄ５０／ＤＳＥＭ＝０．９２であった。
<Example 4>
685 g of lithium hydroxide was dissolved in 4964 g of ion-exchanged water, and the solution was slowly added to 1820 g of orthophosphoric acid to obtain a mixed solution.
On the other hand, 1568 g of goethite particle powder and 3659 g of ion-exchanged water were ball milled for 1 hour using zirconia balls to obtain a slurry of goethite particles. The average secondary particle diameter D 50 of the goethite particles at this time was 1.40 .mu.m.
Next, this slurry was put into a heating type mixing stirrer, the mixed solution and 93 g of ascorbic acid were added while stirring, and the amount of the mixed slurry was adjusted with ion-exchanged water so that the volume became 20 L. Thereafter, the mixture was heated to 95 ° C. with slow stirring, and reacted for 5 hours while maintaining the temperature in the mixing stirrer at 95 ° C. After the reaction, the removed slurry was washed with 5 times the amount of water using a press filter, and then dried with a ventilating dryer for 14 hours to obtain 2796 g of a dry reaction powder.
As a result of observing the obtained dry powder with a scanning microscope, the average secondary particle diameter (D SEM ) of the reaction powder was 1.8 μm, the BET specific surface area was 1.6 m 2 / g, and the particle shape was spherical. It turned out to be a shape. As a result of X-ray diffraction measurement, it was found that the powder had a Tavorite type crystal structure.
This mixture was fired at 550 ° C. for 3 hours in a hydrogen gas atmosphere and crushed.
The resulting carbon content of the calcined product is 0.022 wt%, sulfate ions (SO 4) content 200 ppm, the sodium content is 160 ppm, the results observed with a scanning microscope, the average secondary particle diameter (D SEM ) Was 1.92 μm, the BET specific surface area was 6.0 m 2 / g, the particle shape was spherical, and the compression density was 2.20 g / cc. Further, as a result of X-ray diffraction measurement, it was found to be an olivine type crystal structure. "JEOL HELOS SYSTEM particle size analyzer" average secondary particle diameter D 50 was measured in a 1.76Myuemu, it is confirmed that substantially matches the average secondary particle diameter of the SEM photograph, D 50 / D SEM = 0.92.
＜実施例５＞
水酸化リチウム４２８ｇをイオン交換水３１０２ｇに溶かし、その溶液をオルトリン酸１１３７ｇにゆっくり投入し、混合溶液を得た。
一方、ゲータイト粒子粉末９４２ｇと塩化モリブデン２７ｇとイオン交換水２２１９ｇを、ジルコニアボールを用いて１時間ボールミル処理して、ゲータイト粒子のスラリーを得た。このときのゲータイト粒子粉末の平均二次粒子径Ｄ５０は１．４５μｍであった。
次に、このスラリーを加熱式混合攪拌機に入れ、攪拌しながら前記混合溶液と３７ｇのショ糖を投入し、容積が２０Ｌとなるようイオン交換水で混合スラリーの量を調整した。その後、ゆっくり攪拌しながら９５℃に加熱し、混合攪拌機内の温度を９５℃に保持させた状態で２０時間反応させた。反応後、取り出したスラリー液を、プレスフィルターを用いて５倍量の水で水洗を行った後、１４時間通風式乾燥機で乾燥処理を行い、反応乾燥粉末１７４８ｇを得た。
得られた乾燥粉末を走査型顕微鏡で観察した結果、反応粉末の平均二次粒子径（ＤＳＥＭ）は３．１μｍであり、ＢＥＴ比表面積は１．３ｍ２／ｇであり、粒子形状は球状形であることがわかった。またＸ線回折測定の結果、反応粉末は、Ｔａｖｏｒｉｔｅ型結晶構造であることがわかった。
この混合物を水素ガス雰囲気下、５５０℃にて３時間焼成し、解砕した。
得られた焼成物の炭素含有量は０．０１３ｗｔ％、硫酸イオン（ＳＯ４）含有量は２２０ｐｐｍ、ナトリウム含有量は２２０ｐｐｍであり、組成がＬｉＦｅ０．９９Ｍｏ０．０１ＰＯ４であり、走査型顕微鏡で観察した結果、平均二次粒子径（ＤＳＥＭ）は５．９０μｍ、ＢＥＴ比表面積は６．６ｍ２／ｇ、粒子形状は球状形、圧縮密度は２．１５ｇ／ｃｃであった。またＸ線回折測定の結果、オリビン型結晶構造であることがわかった。「ＪＥＯＬ ＨＥＬＯＳ ＳＹＳＴＥＭ ｐａｒｔｉｃｌｅ ｓｉｚｅ ａｎａｌｙｚｅｒ」で測定した平均二次粒子径Ｄ５０は５．１９μｍであり、ＳＥＭ写真の平均二次粒子径とほぼ一致していることが確認でき、Ｄ５０／ＤＳＥＭ＝０．８８であった。
<Example 5>
Lithium hydroxide (428 g) was dissolved in ion-exchanged water (3102 g), and the solution was slowly added to orthophosphoric acid (1137 g) to obtain a mixed solution.
On the other hand, 942 g of goethite particle powder, 27 g of molybdenum chloride, and 2219 g of ion-exchanged water were ball milled for 1 hour using zirconia balls to obtain a goethite particle slurry. The average secondary particle diameter D 50 of the goethite particles at this time was 1.45 .mu.m.
Next, this slurry was put into a heating type mixing stirrer, the mixed solution and 37 g of sucrose were added while stirring, and the amount of the mixed slurry was adjusted with ion-exchanged water so that the volume became 20 L. Then, it heated at 95 degreeC, stirring slowly, and was made to react for 20 hours, maintaining the temperature in a mixing stirrer at 95 degreeC. After the reaction, the removed slurry was washed with 5 times the amount of water using a press filter, and then dried with a ventilated dryer for 14 hours to obtain 1748 g of a reaction dry powder.
As a result of observing the obtained dry powder with a scanning microscope, the average secondary particle diameter (D SEM ) of the reaction powder was 3.1 μm, the BET specific surface area was 1.3 m 2 / g, and the particle shape was spherical. It turned out to be a shape. As a result of X-ray diffraction measurement, the reaction powder was found to have a Tavorite type crystal structure.
This mixture was fired at 550 ° C. for 3 hours in a hydrogen gas atmosphere and crushed.
The obtained fired product has a carbon content of 0.013 wt%, a sulfate ion (SO 4 ) content of 220 ppm, a sodium content of 220 ppm, a composition of LiFe 0.99 Mo 0.01 PO 4 , and scanning. As a result of observation with a type microscope, the average secondary particle size (D SEM ) was 5.90 μm, the BET specific surface area was 6.6 m 2 / g, the particle shape was spherical, and the compression density was 2.15 g / cc. Further, as a result of X-ray diffraction measurement, it was found to be an olivine type crystal structure. The average secondary particle diameter D 50 measured by “JEOL HELOS SYSTEM particle size analyzer” is 5.19 μm, and it can be confirmed that the average secondary particle diameter of the SEM photograph is almost the same, and D 50 / D SEM = 0.88.
＜比較例１＞
水酸化リチウム２１４ｇイオン交換水１５５１ｇに溶かし、その溶液をオルトリン酸５６９ｇにゆっくり投入し、混合溶液を得た。
次に、平均二次粒子径（Ｄ５０）が１１．４２μｍのゲータイト粒子粉末４７６ｇとイオン交換水１５８７ｇを加熱式混合攪拌機に入れ、攪拌しながら前記混合溶液と１９ｇのショ糖を投入し、容積が１０Ｌとなるようイオン交換水で混合スラリーの量を調整した。その後、ゆっくり攪拌しながら９５℃に加熱し、混合攪拌機内の温度を９５℃に保持させた状態で２０時間反応させた。反応後、取り出したスラリー液を、プレスフィルターを用いて５倍量の水で水洗を行った後、１４時間通風式乾燥機で乾燥処理を行い、反応乾燥粉末８７４ｇを得た。
得られた反応粉末を走査型顕微鏡で観察した結果、反応粉末の平均二次粒子径（ＤＳＥＭ）は１．４μｍであり、ＢＥＴ比表面積は８．５ｍ２／ｇであり、粒子形状は球状形と針状形、不定形の混在であることがわかった。また、Ｘ線回折測定の結果、反応粉末は、Ｔａｖｏｒｉｔｅ型結晶構造以外にα−ＦｅＯＯＨ型とＬｉＨ２ＰＯ４型の混在であることがわかった。得られたＴａｖｏｒｉｔｅ型結晶構造を主とした化合物のＳＥＭ写真を図５に示す。
以降は、実施例１と同様に熱処理を行い、オリビン型複合酸化物を得た。得られた焼成物の炭素含有量は０．０３２ｗｔ％、硫酸イオン（ＳＯ４）含有量は２８０ｐｐｍ、ナトリウム含有量は２５０ｐｐｍであり、走査型顕微鏡で観察した結果、平均二次粒子径（ＤＳＥＭ）は１．２３μｍ、ＢＥＴ比表面積は６．０ｍ２／ｇ、粒子形状は球状形、圧縮密度は１．９６ｇ／ｃｃであった。またＸ線回折測定の結果、オリビン型結晶を主とする構造であることがわかった。得られたオリビン型複合酸化物の電子顕微鏡写真を図６に示す。「ＪＥＯＬ ＨＥＬＯＳ ＳＹＳＴＥＭ ｐａｒｔｉｃｌｅ ｓｉｚｅ ａｎａｌｙｚｅｒ」で測定した平均二次粒子径Ｄ５０は１．８０μｍであり、Ｄ５０／ＤＳＥＭは１．４６であった。
<Comparative Example 1>
Lithium hydroxide 214 g was dissolved in ion-exchanged water 1551 g, and the solution was slowly added to orthophosphoric acid 569 g to obtain a mixed solution.
Next, 476 g of goethite particle powder having an average secondary particle diameter (D 50 ) of 11.42 μm and 1587 g of ion-exchanged water are put into a heating type mixing stirrer, and the mixed solution and 19 g of sucrose are added while stirring. The amount of the mixed slurry was adjusted with ion-exchanged water so as to be 10 L. Then, it heated at 95 degreeC, stirring slowly, and was made to react for 20 hours, maintaining the temperature in a mixing stirrer at 95 degreeC. After the reaction, the slurry liquid taken out was washed with 5 times the amount of water using a press filter, and then dried with a ventilated dryer for 14 hours to obtain 874 g of a reaction dry powder.
As a result of observing the obtained reaction powder with a scanning microscope, the average secondary particle diameter (D SEM ) of the reaction powder was 1.4 μm, the BET specific surface area was 8.5 m 2 / g, and the particle shape was spherical. It turned out to be a mixture of shapes, needles, and irregular shapes. As a result of the X-ray diffraction measurement, it was found that the reaction powder was a mixture of α-FeOOH type and LiH 2 PO 4 type in addition to the Tavorite type crystal structure. FIG. 5 shows an SEM photograph of the compound mainly composed of the obtained Tavorite type crystal structure.
Thereafter, heat treatment was performed in the same manner as in Example 1 to obtain an olivine-type composite oxide. The obtained fired product had a carbon content of 0.032 wt%, a sulfate ion (SO 4 ) content of 280 ppm, and a sodium content of 250 ppm. As a result of observation with a scanning microscope, the average secondary particle size ( DSEM ) Was 1.23 μm, the BET specific surface area was 6.0 m 2 / g, the particle shape was spherical, and the compression density was 1.96 g / cc. Further, as a result of X-ray diffraction measurement, it was found that the structure was mainly composed of olivine crystals. An electron micrograph of the obtained olivine type complex oxide is shown in FIG. The average secondary particle diameter D 50 measured by “JEOL HELOS SYSTEM particle size analyzer” was 1.80 μm, and D 50 / D SEM was 1.46.
＜比較例２＞
水酸化リチウム２５７ｇをイオン交換水１８６２ｇに溶かし、その溶液をオルトリン酸６８２ｇにゆっくり投入し、混合溶液を得た。
一方、ゲータイト粒子粉末５７１ｇとイオン交換水１３３２ｇを、ジルコニアボールを用いて１時間ボールミル処理して、ゲータイト粒子のスラリーを得た。このときのゲータイト粒子粉末の平均二次粒子径Ｄ５０は１．５４μｍであった。
次に、このスラリーを加熱式混合攪拌機に入れ、攪拌しながら前記混合溶液を投入し、容積が２０Ｌとなるようイオン交換水で混合スラリーの量を調整した。その後、ゆっくり攪拌しながら９５℃に加熱し、混合攪拌機内の温度を９５℃に保持させた状態で２０時間、反応させた。その後、混合攪拌機内の温度を１２０℃に昇温させ、反応乾燥粉末１５１０ｇを得た。得られた反応粉末を走査型顕微鏡で観察した結果、反応粉末の平均二次粒子径（ＤＳＥＭ）は２．２μｍであり、ＢＥＴ比表面積は１２，１ｍ２／ｇであり、Ｘ線回折測定の結果、粉末は、α−ＦｅＯＯＨ型とＬｉＨ２ＰＯ４型の混在であることがわかった。以降は、実施例１と同様に熱処理を行い、オリビン型複合酸化物を得た。得られた焼成物の炭素含有量は０．０１５ｗｔ％、硫酸イオン（ＳＯ４）含有量は１５３０ｐｐｍ、ナトリウム含有量は１８２０ｐｐｍであり、走査型顕微鏡で観察した結果、平均二次粒子径（ＤＳＥＭ）は０．３８μｍ、ＢＥＴ比表面積は９．８ｍ２／ｇ、粒子形状は不定形、圧縮密度は１．８８ｇ／ｃｃであった。またＸ線回折測定の結果、オリビン型結晶を主とする構造であることがわかった。「ＪＥＯＬ ＨＥＬＯＳ ＳＹＳＴＥＭ ｐａｒｔｉｃｌｅ ｓｉｚｅ ａｎａｌｙｚｅｒ」で測定した平均二次粒子径Ｄ５０は１．７１μｍであり、Ｄ５０／ＤＳＥＭは４．５０であった。
<Comparative example 2>
257 g of lithium hydroxide was dissolved in 1862 g of ion-exchanged water, and the solution was slowly added to 682 g of orthophosphoric acid to obtain a mixed solution.
On the other hand, 571 g of goethite particle powder and 1332 g of ion-exchanged water were ball milled for 1 hour using zirconia balls to obtain a slurry of goethite particles. The average secondary particle diameter D 50 of the goethite particles at this time was 1.54 .mu.m.
Next, this slurry was put into a heating type mixing stirrer, the mixed solution was added while stirring, and the amount of the mixed slurry was adjusted with ion-exchanged water so that the volume became 20 L. Then, it heated at 95 degreeC, stirring slowly, and was made to react for 20 hours in the state with which the temperature in a mixing stirrer was kept at 95 degreeC. Thereafter, the temperature in the mixing stirrer was raised to 120 ° C. to obtain 1510 g of a dry reaction powder. As a result of observing the obtained reaction powder with a scanning microscope, the average secondary particle diameter (D SEM ) of the reaction powder was 2.2 μm, the BET specific surface area was 12,1 m 2 / g, and X-ray diffraction measurement was performed. As a result, it was found that the powder was a mixture of α-FeOOH type and LiH 2 PO 4 type. Thereafter, heat treatment was performed in the same manner as in Example 1 to obtain an olivine-type composite oxide. Carbon content 0.015 wt% of the obtained baked product, the sulfate ion (SO 4) content 1530 ppm, the sodium content is 1820Ppm, result of observation with a scanning microscope, the average secondary particle diameter (D SEM ) Was 0.38 μm, the BET specific surface area was 9.8 m 2 / g, the particle shape was irregular, and the compression density was 1.88 g / cc. Further, as a result of X-ray diffraction measurement, it was found that the structure was mainly composed of olivine crystals. The average secondary particle diameter D 50 measured by “JEOL HELOS SYSTEM particle size analyzer” was 1.71 μm, and D 50 / D SEM was 4.50.
＜比較例３＞
水酸化リチウム４２８ｇをイオン交換水３１０２ｇに溶かし、その溶液をオルトリン酸１１３７ｇにゆっくり投入し、混合溶液を得た。
一方、ＢＥＴ比表面積が１９．６ｍ２／ｇのマグネタイト粒子粉末７７２ｇ（平均二次粒子径２．０μｍ）とイオン交換水１８０１ｇを、加熱式混合攪拌機に入れ、攪拌しながら前記混合溶液と３７ｇのショ糖を投入し、容積が２０Ｌとなるようイオン交換水で混合スラリーの量を調整した。その後、ゆっくり攪拌しながら９５℃に加熱し、混合攪拌機内の温度を９５℃に保持させた状態で２０時間反応させた。反応後、取り出したスラリー液を、プレスフィルターを用いて５倍量の水で水洗を行った後、１４時間通風式乾燥機で乾燥処理を行い、反応乾燥粉末７４８ｇを得た。得られた反応粉末を走査型顕微鏡で観察した結果、反応粉末の平均二次粒子径（ＤＳＥＭ）は０．２μｍであり、ＢＥＴ比表面積は７．０ｍ２／ｇであった。Ｘ線回折測定の結果、粉末は、Ｆｅ３Ｏ４型結晶構造であることがわかった。オリビン型複合酸化物ではない為、充放電特性の評価は行わなかった。
<Comparative Example 3>
Lithium hydroxide (428 g) was dissolved in ion-exchanged water (3102 g), and the solution was slowly added to orthophosphoric acid (1137 g) to obtain a mixed solution.
On the other hand, 772 g (average secondary particle size 2.0 μm) of magnetite particle powder having a BET specific surface area of 19.6 m 2 / g and 1801 g of ion-exchanged water were put into a heating type mixing stirrer and 37 g of the mixed solution were stirred. Sucrose was added and the amount of the mixed slurry was adjusted with ion-exchanged water so that the volume became 20 L. Then, it heated at 95 degreeC, stirring slowly, and was made to react for 20 hours, maintaining the temperature in a mixing stirrer at 95 degreeC. After the reaction, the removed slurry was washed with 5 times the amount of water using a press filter, and then dried with a ventilated dryer for 14 hours to obtain 748 g of a reaction dry powder. As a result of observing the obtained reaction powder with a scanning microscope, the average secondary particle diameter (D SEM ) of the reaction powder was 0.2 μm, and the BET specific surface area was 7.0 m 2 / g. As a result of X-ray diffraction measurement, it was found that the powder had an Fe 3 O 4 type crystal structure. Since it is not an olivine type complex oxide, the charge / discharge characteristics were not evaluated.
実施例１〜５および比較例１〜３で得られた試料の、鉄原料の平均粒子径、反応混合物の平均二次粒子径および比表面積、反応混合物結晶相、熱処理条件、得られたオリビン型複合酸化物粒子粉末の炭素量、Ｎａ含有量、硫黄含有量、平均二次粒子径（Ｄ５０、ＤＳＥＭ及びその比）、比表面積、形状及び圧縮密度を表１に示す。
なお、比較例のものは、不純物相が存在するせいか、一次粒子の状態から粗大な凝集粒子（２次粒子）まで存在し、分布が広いものであった。また、比較例３については、オリビン型複合酸化物は生成されなかった。
Of the samples obtained in Examples 1 to 5 and Comparative Examples 1 to 3, the average particle diameter of the iron raw material, the average secondary particle diameter and specific surface area of the reaction mixture, the reaction mixture crystal phase, the heat treatment conditions, the obtained olivine type Table 1 shows the carbon content, Na content, sulfur content, average secondary particle size (D 50 , DSEM and ratio thereof), specific surface area, shape and compression density of the composite oxide particle powder.
In addition, the thing of a comparative example existed from the state of a primary particle to the coarse aggregated particle (secondary particle), or the distribution was wide, probably because an impurity phase exists. Moreover, about the comparative example 3, the olivine type complex oxide was not produced | generated.
次に、実施例１〜５および比較例１〜２で得られたオリビン型（ＬｉＦｅＰＯ４）複合酸化物を用いてコインセルによる初期充放電特性評価を行った結果を表２に示す。 Next, Table 2 shows the results of initial charge / discharge characteristics evaluation using coin cells using the olivine type (LiFePO 4 ) composite oxide obtained in Examples 1 to 5 and Comparative Examples 1 and 2.
以上の結果から、本発明に係るオリビン型（ＬｉＦｅＰＯ４）複合酸化物は充放電容量が大きく、充填性及び充放電時のレート特性に優れ、非水電解液電池用活物質として有効であることが確認された。 From the above results, the olivine type (LiFePO 4 ) composite oxide according to the present invention has a large charge / discharge capacity, excellent filling properties and rate characteristics during charge / discharge, and is effective as an active material for non-aqueous electrolyte batteries. Was confirmed.
本発明に係るオリビン型複合酸化物正極活物質を用いることで、充放電容量が大きく、充填性及び保存特性に優れ、電池化時の導電材含有量の制御が容易な非水電解液電池を得ることができる。 By using the olivine-type composite oxide positive electrode active material according to the present invention, a non-aqueous electrolyte battery having a large charge / discharge capacity, excellent filling properties and storage characteristics, and easy control of the conductive material content at the time of battery formation. Can be obtained.
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| JP5729802B2 (en) * | 2009-12-25 | 2015-06-03 | 三菱マテリアル株式会社 | Cathode active material for Li-ion battery and method for producing the same |
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| JP2012204079A (en) * | 2011-03-24 | 2012-10-22 | Nichia Chem Ind Ltd | Olivine-type lithium transition metal oxide and method for producing the same |
| JP5617744B2 (en) * | 2011-03-31 | 2014-11-05 | Tdk株式会社 | Active material particles, active material, electrode, and lithium ion secondary battery |
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| JP2014203589A (en) * | 2013-04-02 | 2014-10-27 | 旭化成株式会社 | Positive electrode active material for nonaqueous electrolyte secondary battery and nonaqueous electrolyte secondary battery |
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