JP7198170B2 - Positive electrode active material for all-solid lithium-ion battery, method for producing positive electrode active material for all-solid-state lithium-ion battery, and all-solid lithium-ion battery - Google Patents

Positive electrode active material for all-solid lithium-ion battery, method for producing positive electrode active material for all-solid-state lithium-ion battery, and all-solid lithium-ion battery Download PDF

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JP7198170B2
JP7198170B2 JP2019140331A JP2019140331A JP7198170B2 JP 7198170 B2 JP7198170 B2 JP 7198170B2 JP 2019140331 A JP2019140331 A JP 2019140331A JP 2019140331 A JP2019140331 A JP 2019140331A JP 7198170 B2 JP7198170 B2 JP 7198170B2
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友哉 田村
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本発明は、全固体リチウムイオン電池用正極活物質、全固体リチウムイオン電池用正極活物質の製造方法及び全固体リチウムイオン電池に関する。 TECHNICAL FIELD The present invention relates to a positive electrode active material for an all-solid lithium ion battery, a method for producing a positive electrode active material for an all-solid lithium-ion battery, and an all-solid lithium-ion battery.

近年におけるパソコン、ビデオカメラ、及び携帯電話等の情報関連機器や通信機器等の急速な普及に伴い、その電源として利用される電池の開発が重要視されている。該電池の中でも、エネルギー密度が高いという観点から、リチウム電池が注目を浴びている。また、車載用等の動力源やロードレべリング用といった大型用途におけるリチウム二次電池についても、高エネルギー密度、電池特性向上が求められている。 2. Description of the Related Art In recent years, with the rapid spread of information-related equipment and communication equipment such as personal computers, video cameras, and mobile phones, the development of batteries used as power sources for these devices has been emphasized. Among these batteries, lithium batteries are attracting attention because of their high energy density. High energy density and improved battery characteristics are also required for lithium secondary batteries used in large-scale applications such as power sources for vehicles and load leveling.

ただ、リチウムイオン電池の場合は、電解液は有機化合物が大半であり、たとえ難燃性の化合物を用いたとしても火災に至る危険性が全くなくなるとは言いきれない。こうした液系リチウムイオン電池の代替候補として、電解質を固体とした全固体リチウムイオン電池が近年注目を集めている。 However, in the case of lithium-ion batteries, most of the electrolytes are organic compounds, and even if flame-retardant compounds are used, the risk of fire cannot be completely eliminated. In recent years, all-solid-state lithium-ion batteries with a solid electrolyte have been attracting attention as a candidate to replace such liquid-type lithium-ion batteries.

全固体リチウムイオン電池用正極活物質として、セル作製でプレスする際に割れにくい、または、表面が滑らかなためコーティングを行い易いといった理由から単粒子の正極活物質が求められている。従来、酸化物であるＣｏ3Ｏ4とＬｉ源とを混合して焼成して得られるＬｉＣｏＯ2のような正極活物質が単粒子に近く、プレス時の割れが少ない正極となる。このため、特に酸化物系固体電解質を用いる全固体電池では、当該材料を用いることが主流となっている。 As a positive electrode active material for all-solid-state lithium ion batteries, there is a demand for a single-particle positive electrode active material for the reasons that it is less likely to crack when pressed in cell fabrication, and that it is easy to coat due to its smooth surface. Conventionally, a positive electrode active material such as LiCoO 2 obtained by mixing an oxide of Co 3 O 4 and a Li source and firing the mixture is close to a single particle and serves as a positive electrode with less cracking during pressing. For this reason, especially in an all-solid-state battery using an oxide-based solid electrolyte, the use of this material has become mainstream.

一方、同じ層状のＲ３－ｍの結晶構造をとるＮｉ－Ｃｏ－ＭｎやＮｉ－Ｃｏ－Ａｌといった３元系の正極活物質は、共沈法により水酸化物の前駆体を出発原料としている。しかしながら、このような出発原料では、元の水酸化物の粒子が小さいために、Ｌｉ源と混練して焼成を行っても細かい一次粒子が凝集した二次粒子が形成された正極活物質となってしまい、単粒子化が困難となっている。 On the other hand, ternary positive electrode active materials such as Ni--Co--Mn and Ni--Co--Al having the same layered R3-m crystal structure use a hydroxide precursor as a starting material by a coprecipitation method. However, in such a starting material, since the particles of the original hydroxide are small, even if kneading with the Li source and firing are performed, the positive electrode active material is formed with secondary particles in which fine primary particles are aggregated. Therefore, it is difficult to form single particles.

ここで、従来の正極活物質を製造する技術として、例えば、非特許文献１には、共沈水酸化物前駆体を用いて単粒子ＮｉＣｏＭｎ系正極活物質を作製する技術が開示されている。当該文献によれば、ＮｉＣｏＭｎの酸化物のような層状構造より、ＬｉＭｎの酸化物のようなスピネル構造を取る方が、同じ温度で焼成しても粒成長し易いと記載されている。そして、ＮｉＣｏＭｎの組成におけるＭｎ相当分のＬｉを添加して、まず１０００℃で焼成し、スピネル・酸化物の中間体を作製し、その後、足りないＬｉを当該中間体へ添加し、９００℃で焼成することで単粒子正極を得ることができると記載されている。 Here, as a conventional technique for producing a positive electrode active material, for example, Non-Patent Document 1 discloses a technique for producing a single-particle NiCoMn-based positive electrode active material using a coprecipitated hydroxide precursor. According to the literature, it is described that a spinel structure like an oxide of LiMn is more likely to grow grains than a layered structure like an oxide of NiCoMn even if fired at the same temperature. Then, Li corresponding to Mn in the composition of NiCoMn is added, first fired at 1000 ° C. to prepare a spinel-oxide intermediate, after that, the missing Li is added to the intermediate and heated at 900 ° C. It is described that a single-particle positive electrode can be obtained by firing.

また、従来の高強度の正極活物質の製造方法として、例えば、特許文献１には、リチウム化合物と、ニッケル及びマンガンを含む遷移金属化合物とを含有する第１混合物を焼成する第１焼成工程と、第１焼成工程により得られた前駆体粒子に更にリチウム化合物を添加してなる第２混合物を焼成する第２焼成工程とを含む、２回以上の焼成工程を備え、第１混合物におけるリチウムの含有量は遷移金属の総量に対するモル比で０．５未満であり、第２混合物におけるリチウムの含有量は遷移金属の総量に対するモル比で０．９以上１．１以下である非水電解質二次電池用正極活物質の製造方法が開示されている。 Further, as a conventional method for producing a high-strength positive electrode active material, for example, Patent Document 1 discloses a first firing step of firing a first mixture containing a lithium compound and a transition metal compound containing nickel and manganese. and a second firing step of firing a second mixture obtained by further adding a lithium compound to the precursor particles obtained in the first firing step. The content is less than 0.5 in molar ratio with respect to the total amount of transition metals, and the content of lithium in the second mixture is 0.9 or more and 1.1 or less in molar ratio with respect to the total amount of transition metals. A method for manufacturing a positive electrode active material for a battery is disclosed.

特開２０１７－１５７５４８号公報JP 2017-157548 A

Ｊｏｕｒｎａｌ ｏｆ Ｍａｔｅｒｉａｌｓ Ｃｈｅｍｉｓｔｒｙ Ａ，２０１８，６，１２３４４－１２３５２Journal of Materials Chemistry A, 2018, 6, 12344-12352

Ｎｉ－Ｃｏ－Ｍｎ系のリチウムイオン電池用正極活物質は、組成比：Ｎｉ／Ｎｉ＋Ｃｏ＋Ｍｎが０．８以上という高いＮｉ含有率を有することで、電池特性等が向上することが知られている。しかしながら、非特許文献１及び特許文献１に記載された正極活物質は、遷移金属の組成がＮｉ：Ｃｏ：Ｍｎ＝１：１：１であり、Ｎｉの組成比が低い正極活物質である。 Ni—Co—Mn-based positive electrode active materials for lithium ion batteries are known to improve battery characteristics and the like by having a high Ni content of 0.8 or more in a composition ratio of Ni/Ni+Co+Mn. However, the positive electrode active material described in Non-Patent Document 1 and Patent Document 1 has a transition metal composition of Ni:Co:Mn=1:1:1 and a low Ni composition ratio.

また、リチウムイオン電池用正極活物質は、高強度であることの他、電池に使用したときの出力特性が良好であることも重要な特性である。ここで、例えば、充放電時のＬｉイオンの移動に寄与しないＮｉＯなどの相がリチウムイオン電池用正極活物質に含まれているような場合、電池容量が著しく低下するおそれがある。一方、リチウムイオン電池用正極活物質を単一相に制御することができれば、電池容量が良好になる効果が期待できる。 In addition to high strength, the positive electrode active material for lithium ion batteries also has good output characteristics when used in batteries. Here, for example, if the positive electrode active material for a lithium ion battery contains a phase such as NiO that does not contribute to movement of Li ions during charging and discharging, the battery capacity may significantly decrease. On the other hand, if the positive electrode active material for lithium ion batteries can be controlled to have a single phase, the effect of improving the battery capacity can be expected.

このような問題に鑑み、本発明の実施形態は、Ｎｉ組成比が高く、且つ、単一相で高強度を有する全固体リチウムイオン電池用正極活物質を提供することを課題とする。 In view of such problems, an object of the embodiments of the present invention is to provide a positive electrode active material for an all-solid-state lithium-ion battery that has a high Ni composition ratio, a single phase, and high strength.

本発明は一実施形態において、組成式：ＬｉaＮｉbＣｏcＭｎdＯ2
（式中、１．０≦ａ≦１．１０、０．８≦ｂ≦０．９、０．０５≦ｃ≦０．１９、０．０１≦ｄ≦０．１、ｂ＋ｃ＋ｄ＝１である。）
で表され、平均粒子径Ｄ５０が２μｍ以上であり、粒子強度が３００ＭＰａ以上であり、層状岩塩構造となる空間群Ｒ３－ｍに帰属する単一相であり、単粒子の比率が８０％以上である全固体リチウムイオン電池用正極活物質である。 In one embodiment of the present invention, the composition formula: Li a Ni b Co c Mnd O 2
(wherein 1.0≦a≦1.10, 0.8≦b≦0.9, 0.05≦c≦0.19, 0.01≦d≦0.1, and b+c+d=1. )
and has an average particle diameter D50 of 2 μm or more, a particle strength of 300 MPa or more, a single phase belonging to the space group R3-m with a layered rock salt structure, and a single particle ratio of 80% or more. It is a cathode active material for an all-solid-state lithium-ion battery.

本発明の全固体リチウムイオン電池用正極活物質は一実施形態において、前記平均粒子径Ｄ５０が２μｍ以上６μｍ以下で、且つ、粒子強度が３００ＭＰａ以上８００ＭＰａ以下である。 In one embodiment, the positive electrode active material for an all-solid-state lithium ion battery of the present invention has an average particle size D50 of 2 μm or more and 6 μm or less and a particle strength of 300 MPa or more and 800 MPa or less.

本発明は別の一実施形態において、共沈法で作製されたＮｉＣｏＭｎ系金属水酸化物を準備する工程１と、Ｌｉが、前記ＮｉＣｏＭｎ系金属水酸化物におけるＮｉ、Ｃｏ及びＭｎの合計モル比の２０％以下のモル比となるように、前記ＮｉＣｏＭｎ系金属水酸化物にリチウム塩を添加し、８５０℃以上で一次焼成する工程２と、前記一次焼成後に得られた粉体に、前記工程２で添加したリチウム塩との合計で、Ｌｉが、前記ＮｉＣｏＭｎ系金属水酸化物におけるＮｉ、Ｃｏ及びＭｎの合計モル比と同じモル比以上となるように、更にリチウム塩を添加し、７８０℃以上で二次焼成する工程３と、を含む本発明の実施形態に係る全固体リチウムイオン電池用正極活物質の製造方法である。 In another embodiment of the present invention, step 1 of preparing a NiCoMn-based metal hydroxide produced by a coprecipitation method, Li is the total molar ratio of Ni, Co and Mn in the NiCoMn-based metal hydroxide Step 2 of adding a lithium salt to the NiCoMn-based metal hydroxide so that the molar ratio is 20% or less and performing primary firing at 850 ° C. or higher, and the powder obtained after the primary firing is added to the step Lithium salt was further added so that the total molar ratio of Li, together with the lithium salt added in 2, was equal to or higher than the total molar ratio of Ni, Co and Mn in the NiCoMn-based metal hydroxide, and the temperature was 780 ° C. It is a manufacturing method of the positive electrode active material for all-solid-state lithium ion batteries according to the embodiment of the present invention, including the step 3 of secondary firing as described above.

本発明の全固体リチウムイオン電池用正極活物質の製造方法は一実施形態において、前記共沈法は、ニッケル塩、コバルト塩及びマンガン塩の混合物の水溶液に、アンモニア水及び水酸化ナトリウムを加えてＮｉＣｏＭｎ系金属水酸化物を得る方法である。 In one embodiment of the method for producing a positive electrode active material for an all-solid-state lithium ion battery of the present invention, the coprecipitation method comprises adding aqueous ammonia and sodium hydroxide to an aqueous solution of a mixture of nickel salt, cobalt salt and manganese salt. This is a method for obtaining a NiCoMn-based metal hydroxide.

本発明は更に別の一実施形態において、正極層、負極層及び固体電解質層を備え、本発明の実施形態に係る全固体リチウムイオン電池用正極活物質を前記正極層に備えた全固体リチウムイオン電池である。 In still another embodiment of the present invention, an all-solid lithium ion comprising a positive electrode layer, a negative electrode layer and a solid electrolyte layer, and having the positive electrode active material for an all-solid lithium ion battery according to the embodiment of the present invention in the positive electrode layer Battery.

本発明の実施形態によれば、Ｎｉ組成比が高く、且つ、単一相で高強度を有する全固体リチウムイオン電池用正極活物質を提供することができる。 According to the embodiments of the present invention, it is possible to provide a positive electrode active material for an all-solid-state lithium-ion battery that has a high Ni composition ratio, a single phase, and high strength.

粒子の包絡度を説明するための粒子の投影図である。FIG. 4 is a projection view of particles for explaining the degree of envelopment of particles; 乾式粒子画像分析装置：Ｍｏｒｐｈｏｌｏｇｉ Ｇ３（Ｍａｌｖｅｒｎ Ｐａｎａｌｙｔｉｃａｌ社製）を用いて測定した粒子の包絡度の例を示す図である。It is a figure which shows the example of the envelopment degree of the particle measured using the dry particle image analyzer: Morphologi G3 (manufactured by Malvern Panalytical). 実施例１及び比較例１で得られた各正極活物質のＸＲＤチャートである。4 is an XRD chart of each positive electrode active material obtained in Example 1 and Comparative Example 1. FIG.

（正極活物質の構成）
本発明の実施形態に係る全固体リチウムイオン電池用正極活物質は、組成式：ＬｉaＮｉbＣｏcＭｎdＯ2
（式中、１．０≦ａ≦１．１０、０．８≦ｂ≦０．９、０．０５≦ｃ≦０．１９、０．０１≦ｄ≦０．１、ｂ＋ｃ＋ｄ＝１である。）で表される。 (Structure of positive electrode active material)
A positive electrode active material for an all - solid lithium ion battery according to an embodiment of the present invention has a composition formula : LiaNibCocMndO2
(wherein 1.0≦a≦1.10, 0.8≦b≦0.9, 0.05≦c≦0.19, 0.01≦d≦0.1, and b+c+d=1. ).

本発明の実施形態に係る全固体リチウムイオン電池用正極活物質において、Ｌｉの組成が１．０未満では、リチウム量が不足して安定した結晶構造を保持しにくく、１．１０を超えると当該正極活物質を用いて作製した全固体リチウムイオン電池の放電容量が低くなるおそれがある。 In the positive electrode active material for an all-solid lithium ion battery according to the embodiment of the present invention, if the Li composition is less than 1.0, the amount of lithium is insufficient and it is difficult to maintain a stable crystal structure, and if it exceeds 1.10, the There is a possibility that the discharge capacity of an all-solid-state lithium-ion battery produced using the positive electrode active material may be lowered.

正極活物質の組成は、誘導結合プラズマ発光分光分析装置（ＩＣＰ－ＯＥＳ）及びイオンクロマトグラフ法により測定することができる。 The composition of the positive electrode active material can be measured by an inductively coupled plasma-optical emission spectrometer (ICP-OES) and ion chromatography.

本発明の実施形態に係る全固体リチウムイオン電池用正極活物質の平均粒子径Ｄ５０は２μｍ以上に制御されている。このような構成によれば、固体電解質と正極活物質との接触面積が大きくなり、正極活物質と固体電解質との間のＬｉイオンの伝導性が良好となる。当該平均粒子径Ｄ５０は２．５μｍ以上であってもよく、３μｍ以上であってもよい。また、当該平均粒子径Ｄ５０は６μｍ以下であってもよく、５μｍ以下であってもよく、４．５μｍ以下であってもよく、３．５μｍ以下であってもよく、３μｍ以下であってもよい。 The average particle diameter D50 of the positive electrode active material for all-solid lithium ion batteries according to the embodiment of the present invention is controlled to 2 μm or more. With such a configuration, the contact area between the solid electrolyte and the positive electrode active material is increased, and the conductivity of Li ions between the positive electrode active material and the solid electrolyte is improved. The average particle diameter D50 may be 2.5 µm or more, or may be 3 µm or more. In addition, the average particle diameter D50 may be 6 μm or less, 5 μm or less, 4.5 μm or less, 3.5 μm or less, or 3 μm or less. good.

本発明の実施形態に係る全固体リチウムイオン電池用正極活物質の平均粒子径Ｄ５０は、Ｍｉｃｒｏｔｒａｃ製ＭＴ３３００ＥＸII等の粒子径測定装置により測定することができる。 The average particle size D50 of the positive electrode active material for all solid state lithium ion batteries according to the embodiment of the present invention can be measured with a particle size measuring device such as MT3300EXII manufactured by Microtrac.

本発明の実施形態に係る全固体リチウムイオン電池用正極活物質の粒子強度は、３００ＭＰａ以上に制御されている。従来の電解液を用いた電池では、粒子がプレス時に割れても流動性の高い電解液がその隙間に染み込むが、全固体電池では、割れで生じた空隙の間に固体の電解質が入り込むことはないため、そこで導電パスが途切れ出力低下を招く。これに対し、本発明の実施形態に係る全固体リチウムイオン電池用正極活物質を用いることにより、高強度で割れにくい正極が得られ、これによって高出力な全固体電池を作製することが可能となる。当該正極活物質の粒子強度は、３５０ＭＰａ以上であるのが好ましく、４００ＭＰａ以上であるのがより好ましい。当該正極活物質の粒子強度の上限値は特に限定されないが、例えば、８００ＭＰａ以下であってもよく、７００ＭＰａ以下であってもよく、６００ＭＰａ以下であってもよい。 The particle strength of the positive electrode active material for all-solid lithium ion batteries according to the embodiment of the present invention is controlled to 300 MPa or more. In batteries using conventional electrolytes, even if the particles crack during pressing, the highly fluid electrolyte seeps into the gaps, but in all-solid-state batteries, the solid electrolyte does not enter the gaps created by the cracks. Therefore, the conductive path is interrupted there, resulting in a decrease in output. On the other hand, by using the positive electrode active material for an all-solid-state lithium ion battery according to the embodiment of the present invention, a high-strength and hard-to-crack positive electrode can be obtained, thereby making it possible to produce a high-output all-solid-state battery. Become. The particle strength of the positive electrode active material is preferably 350 MPa or more, more preferably 400 MPa or more. Although the upper limit of the particle strength of the positive electrode active material is not particularly limited, it may be, for example, 800 MPa or less, 700 MPa or less, or 600 MPa or less.

本発明の実施形態に係る全固体リチウムイオン電池用正極活物質の粒子強度は、以下のようにして島津製作所製微小圧縮試験機ＭＣＴ－２１１にて測定することができる。すなわち、分散させた粉末サンプルを試料台に置き、顕微鏡で平均粒子径Ｄ５０サイズの２次粒子一粒の中心を狙い、２０μｍの径の圧子を負荷速度０．５３２ｍＮ／ｓｅｃで押し付け、破断した際の強度をＮ＝１０で測定し、その平均値を各サンプルの粒子強度とする。 The particle strength of the positive electrode active material for all-solid-state lithium ion batteries according to the embodiment of the present invention can be measured using a microcompression tester MCT-211 manufactured by Shimadzu Corporation as follows. That is, place the dispersed powder sample on the sample stage, aim at the center of one secondary particle with an average particle size of D50 size with a microscope, press an indenter with a diameter of 20 μm at a load rate of 0.532 mN / sec, and break it. is measured at N=10, and the average value is taken as the particle strength of each sample.

本発明の実施形態に係る全固体リチウムイオン電池用正極活物質は、層状岩塩構造となる空間群Ｒ３－ｍに帰属する単一相である。層状岩塩構造は、遷移金属とリチウムとが規則的に配列して二次元平面を形成して、リチウムが二次元拡散する構造を有している。このため、本発明の実施形態に係る全固体リチウムイオン電池用正極活物質が、層状岩塩構造となる空間群Ｒ３－ｍに帰属する単一相であると、充放電時のＬｉイオンの移動に寄与しないＮｉＯなどの相が無いため、電池容量が良好になる効果が期待できる。 A positive electrode active material for an all-solid-state lithium ion battery according to an embodiment of the present invention has a single phase belonging to the space group R3-m and has a layered rock salt structure. The layered rock salt structure has a structure in which transition metals and lithium are regularly arranged to form a two-dimensional plane, and lithium diffuses two-dimensionally. For this reason, if the positive electrode active material for an all-solid-state lithium ion battery according to the embodiment of the present invention is a single phase belonging to the space group R3-m having a layered rock salt structure, the movement of Li ions during charging and discharging Since there is no phase such as NiO that does not contribute, the effect of improving the battery capacity can be expected.

一般に、正極活物質を構成する一次粒子が層状岩塩構造を有することは、粉末Ｘ線回折法に基づく公知の方法で解析及び同定することができる。例えば、正極活物質のＸ線回折パターンにおいて、主に回折角（２θ）＝１８．７°付近の（００３）面、３６．６°付近の（１０１）面、３８．３°付近の（０１２）面、４４．４°付近の（１０４）面、４８．６°付近の（０１５）面、５８．６°付近の（１０７）面、６４．４°付近の（０１８）面、６４．８°付近の（１１０）面、及び６８．０°付近等に出現する（１１３）面の計９本の空間群Ｒ３－ｍに帰属する回折ピークを検出することによって、層状岩塩構造の存在が確認される。これらピークのみが観察されると、層状岩塩構造となる空間群Ｒ３－ｍに帰属する単一相であると判断することができる。 In general, the fact that the primary particles constituting the positive electrode active material have a layered rock salt structure can be analyzed and identified by a known method based on powder X-ray diffractometry. For example, in the X-ray diffraction pattern of the positive electrode active material, mainly the (003) plane near the diffraction angle (2θ) = 18.7°, the (101) plane near 36.6°, the (012) plane near 38.3° ) plane, (104) plane near 44.4°, (015) plane near 48.6°, (107) plane near 58.6°, (018) plane near 64.4°, 64.8 The existence of a layered rock salt structure is confirmed by detecting the diffraction peaks attributed to a total of nine space groups R3-m, the (110) plane near 68.0° and the (113) plane appearing near 68.0°. be done. When only these peaks are observed, it can be determined that the crystal is a single phase belonging to the space group R3-m, which has a layered rock salt structure.

また、例えば、正極活物質を構成する一次粒子が単一相でない場合は、正極活物質のＸ線回折パターンにおいて、ＮｉＯのピークが３７．５°、４３．５°、６３．５°付近に観察される。 Further, for example, when the primary particles constituting the positive electrode active material are not in a single phase, the X-ray diffraction pattern of the positive electrode active material has NiO peaks near 37.5°, 43.5°, and 63.5°. Observed.

本発明の実施形態に係る全固体リチウムイオン電池用正極活物質は、単粒子の比率が８０％以上に制御されている。単粒子の比率が８０％以上であると、正極活物質が高強度を有することとなり、電池の作製工程で正極活物質をプレスする際に割れ難くなる。正極活物質の単粒子の比率は、８５％以上が好ましく、９０％以上がより好ましく、９５％以上がさらにより好ましい。 The positive electrode active material for an all-solid-state lithium ion battery according to an embodiment of the present invention has a single particle ratio controlled to 80% or more. When the ratio of the single particles is 80% or more, the positive electrode active material has high strength, and the positive electrode active material is less likely to crack when pressed in the manufacturing process of the battery. The ratio of single particles of the positive electrode active material is preferably 85% or more, more preferably 90% or more, and even more preferably 95% or more.

正極活物質の単粒子の比率は、粒子の包絡度から求める。ここで、粒子の包絡度は粒子の輪郭に基づいて測定する。粒子の輪郭は、凝集した粒子の検出に加えて、表面粗さなどの特性についての情報を提供する。粒子輪郭パラメータを計算するには、凸包周囲長と呼ばれる概念を使用する。凸包周囲長は、図１に示すように、粒子の輪郭の周囲に巻き付けた仮想の輪ゴムから計算する。 The ratio of single particles of the positive electrode active material is obtained from the degree of envelopment of the particles. Here, the envelopment of a particle is measured based on the contour of the particle. Particle contours provide information about properties such as surface roughness in addition to detecting agglomerated particles. A concept called the convex hull perimeter is used to calculate the particle contour parameter. The convex hull perimeter is calculated from a virtual rubber band wrapped around the contour of the particle, as shown in FIG.

図１では、粒子Ａは外周に凹凸がほぼ無い形状を有しており、粒子の輪郭の周囲に巻き付けた仮想の輪ゴムの長さ（凸包周囲長）は、粒子Ａの外周の長さ（粒子Ａの実際の周囲長）とほぼ等しくなる。一方、粒子Ｂは外周に凹凸があり、粒子の輪郭の周囲に巻き付けた仮想の輪ゴムの長さ（凸包周囲長）は、粒子Ｂの外周の長（粒子Ｂの実際の周囲長）さより小さくなる。このとき、以下の式で定義されるのが「粒子の包絡度」である。粒子の周囲に凹凸が無いほど、粒子の包絡度の数値が１．０に近くなる。
粒子の包絡度＝凸包周囲長／粒子の実際の周囲長 In FIG. 1, the particle A has a shape with almost no unevenness on the outer periphery, and the length of the virtual rubber band wrapped around the contour of the particle (peripheral length of the convex hull) is the length of the outer periphery of the particle A ( is approximately equal to the actual perimeter of particle A). On the other hand, particle B has an uneven outer periphery, and the length of the imaginary rubber band wrapped around the contour of particle (convex hull perimeter) is smaller than the outer perimeter of particle B (actual perimeter of particle B). Become. At this time, the “particle envelopment degree” is defined by the following equation. The smaller the unevenness around the particle, the closer the numerical value of the particle envelopment to 1.0.
Particle Envelope = Convex Hull Perimeter / Particle Actual Perimeter

粒子の包絡度は、以下のようにして測定することができる。すなわち、乾式粒子画像分析装置：Ｍｏｒｐｈｏｌｏｇｉ Ｇ３（Ｍａｌｖｅｒｎ Ｐａｎａｌｙｔｉｃａｌ社製）にて、約１万個の粉体粒子を測定する。測定は、サンプルカートリッジに対象となる正極活物質の粉体粒子を投入し、ガラスプレート上に当該正極活物質の粉体粒子を分散させ、粒子の投影画像を撮影し、粉体粒子の２次元形状を得る。得られた２次元形状の解析で、粒子の包絡度が計算され、上述の「凸包周囲長／粒子の実際の周囲長」で定義される。 Particle envelopment can be measured as follows. That is, about 10,000 powder particles are measured with a dry particle image analyzer: Morphologi G3 (manufactured by Malvern Panalytical). In the measurement, the powder particles of the positive electrode active material to be targeted are put into a sample cartridge, the powder particles of the positive electrode active material are dispersed on a glass plate, the projection image of the particles is taken, and the two-dimensional measurement of the powder particles is performed. get the shape. By analyzing the resulting two-dimensional shape, the envelopment of the particle is calculated and defined by the above-mentioned "convex hull perimeter/actual perimeter of the particle".

乾式粒子画像分析装置：Ｍｏｒｐｈｏｌｏｇｉ Ｇ３（Ｍａｌｖｅｒｎ Ｐａｎａｌｙｔｉｃａｌ社製）を用いて測定した粒子の包絡度の例として、図２を示す。図２は、６つの粒子の形状と、各粒子の包絡度を示している。粒子Ｃ、Ｄ、Ｅ及びＦ、Ｇ及びＨの順に徐々に粒子の外周の凹凸が小さくなっていき、輪郭が滑らかになっている。それに従い、粒子の包絡度も徐々に１．０に近くなっていることがわかる。特に、図２の粒子Ｅ及びＦ、更に粒子Ｇ及びＨでは単粒子を形どっており、このときの包絡度が０．９８以上となっていることがわかる。本発明の実施形態に係る全固体リチウムイオン電池用正極活物質は、上述のようにして定義される粒子の包絡度が０．９８以上のものを単粒子と定義している。 FIG. 2 shows an example of particle envelopment measured using a dry particle image analyzer: Morphologi G3 (manufactured by Malvern Panalytical). FIG. 2 shows the shape of six particles and the envelopment of each particle. In the order of particles C, D, E and F, G and H, the unevenness of the outer periphery of the particles gradually decreases, and the outline becomes smooth. Accordingly, it can be seen that the envelopment degree of the particles gradually approaches 1.0. In particular, particles E and F, and particles G and H in FIG. 2 are in the form of single particles, and the enveloping degree at this time is 0.98 or more. In the positive electrode active material for an all-solid lithium ion battery according to the embodiment of the present invention, a single particle is defined as having an envelopment degree of 0.98 or more as defined above.

（全固体リチウムイオン電池用正極活物質の製造方法）
次に、本発明の実施形態に係る全固体リチウムイオン電池用正極活物質の製造方法について詳述する。本発明の実施形態に係る全固体リチウムイオン電池用正極活物質の製造方法は、まず、共沈法で作製されたＮｉＣｏＭｎ系金属水酸化物を準備する。当該共沈法は、ニッケル塩、コバルト塩及びマンガン塩の混合物の水溶液に、アンモニア水を加え撹拌しながら、水酸化ナトリウムを加えてＮｉＣｏＭｎ系金属水酸化物を得る方法であるのが好ましい。当該共沈法において、反応液中のｐＨは、１０．５～１１．５、アンモニウムイオン濃度は１０～２５ｇ／Ｌ、液温を５０～６５℃に制御することが好ましい。 (Method for producing positive electrode active material for all-solid-state lithium ion battery)
Next, a method for producing a positive electrode active material for an all-solid-state lithium ion battery according to an embodiment of the present invention will be described in detail. In the method for producing a positive electrode active material for an all-solid-state lithium-ion battery according to an embodiment of the present invention, first, a NiCoMn-based metal hydroxide produced by a coprecipitation method is prepared. The coprecipitation method is preferably a method of obtaining a NiCoMn-based metal hydroxide by adding aqueous ammonia to an aqueous solution of a mixture of nickel salt, cobalt salt and manganese salt and adding sodium hydroxide while stirring. In the coprecipitation method, it is preferable to control the pH of the reaction liquid to 10.5 to 11.5, the ammonium ion concentration to 10 to 25 g/L, and the liquid temperature to 50 to 65°C.

共沈法で作製されたＮｉＣｏＭｎ系金属水酸化物は、ＮｉbＣｏcＭｎd（ＯＨ）2（式中、０．８≦ｂ≦０．９、０．０５≦ｃ≦０．１９、０．０１≦ｄ≦０．１、ｂ＋ｃ＋ｄ＝１である。）で表される組成を有することが好ましい。 The NiCoMn-based metal hydroxide produced by the coprecipitation method is Ni b Co c Mnd (OH) 2 (wherein 0.8≦b≦0.9, 0.05≦c≦0.19, 0 .01≤d≤0.1 and b+c+d=1).

次に、ＮｉＣｏＭｎ系金属水酸化物にリチウム塩を添加する。このとき、Ｌｉが、ＮｉＣｏＭｎ系金属水酸化物におけるＮｉ、Ｃｏ及びＭｎの合計モル比の２０％以下のモル比となるように添加する。例えば、ＮｉＣｏＭｎ系金属水酸化物におけるＮｉ、Ｃｏ及びＭｎの合計モル比が１．０である場合、Ｌｉのモル比が０．２以下となるようにリチウム塩を添加する。 Next, a lithium salt is added to the NiCoMn-based metal hydroxide. At this time, Li is added so that the molar ratio is 20% or less of the total molar ratio of Ni, Co and Mn in the NiCoMn-based metal hydroxide. For example, when the total molar ratio of Ni, Co and Mn in the NiCoMn-based metal hydroxide is 1.0, the lithium salt is added so that the molar ratio of Li is 0.2 or less.

ＮｉＣｏＭｎ系金属水酸化物に添加するリチウム塩は、例えば、炭酸リチウム、水酸化リチウム等が挙げられる。 Examples of the lithium salt added to the NiCoMn-based metal hydroxide include lithium carbonate and lithium hydroxide.

次に、リチウム塩を添加したＮｉＣｏＭｎ系金属水酸化物を、８５０℃以上で一次焼成して粉体を得る。当該一次焼成の加熱温度は９００℃以上であってもよく、１０００℃以上であってもよい。また、当該一次焼成の加熱温度は１１００℃以上であってもよい。当該一次焼成の加熱時間は、加熱温度との関係から適宜設定することができるが、例えば、加熱温度が８５０℃～１１００℃の場合、６～１０時間とすることができる。 Next, the NiCoMn-based metal hydroxide to which the lithium salt is added is primarily sintered at 850° C. or higher to obtain powder. The heating temperature for the primary firing may be 900° C. or higher, or 1000° C. or higher. Also, the heating temperature for the primary firing may be 1100° C. or higher. The heating time for the primary firing can be appropriately set depending on the relationship with the heating temperature. For example, when the heating temperature is 850.degree. C. to 1100.degree.

次に、一次焼成後に得られた粉体に、更にリチウム塩を添加する。このとき、ＮｉＣｏＭｎ系金属水酸化物に対して添加したリチウム塩との合計で、ＮｉＣｏＭｎ系金属水酸化物におけるＮｉ、Ｃｏ及びＭｎの合計モル比以上となるように、更にリチウム塩を添加する。例えば、ＮｉＣｏＭｎ系金属水酸化物におけるＮｉ、Ｃｏ及びＭｎの合計モル比が１．０であり、一次焼成の前にＬｉのモル比が０．２となるようにリチウム塩を添加した場合、ここでは、Ｌｉのモル比が０．８以上となるようにリチウム塩を添加する。 Next, a lithium salt is further added to the powder obtained after the primary firing. At this time, the lithium salt is further added so that the total molar ratio of Ni, Co, and Mn in the NiCoMn-based metal hydroxide is equal to or greater than the total molar ratio of the lithium salt added to the NiCoMn-based metal hydroxide. For example, when the total molar ratio of Ni, Co, and Mn in the NiCoMn-based metal hydroxide is 1.0, and a lithium salt is added so that the molar ratio of Li is 0.2 before primary firing, here Then, a lithium salt is added so that the molar ratio of Li is 0.8 or more.

一次焼成後に、更に添加するリチウム塩は、水酸化リチウムであるのが好ましい。水酸化リチウムは融点が４６２℃であり、本発明の実施形態に係る高いＮｉ組成（モル比０．８以上）を有する正極活物質の融点（例えば７００℃程度）より低い。このため、後述の二次焼成によって、添加した水酸化リチウムのＬｉが一次焼成後の粉体と良好に反応することができる。 The lithium salt to be further added after the primary firing is preferably lithium hydroxide. Lithium hydroxide has a melting point of 462.degree. Therefore, Li of the added lithium hydroxide can react well with the powder after the primary firing by the secondary firing described later.

次に、上述のように更にリチウム塩を添加した粉体を、７８０℃以上で二次焼成する。このようにして、本発明の実施形態に係る全固体リチウムイオン電池用正極活物質を作製することができる。 Next, the powder to which the lithium salt is further added as described above is subjected to secondary firing at 780° C. or higher. In this manner, a positive electrode active material for an all-solid lithium ion battery according to an embodiment of the present invention can be produced.

当該二次焼成の加熱温度は、９００℃以上の高温では酸素の脱離、Ｌｉの揮発等が生じるため９００℃以下、より好ましくは８５０℃以下であると良い。当該二次焼成の加熱時間は、加熱温度との関係から適宜設定することができるが、例えば、加熱温度が７８０～８５０℃の場合、４～１２時間とすることができる。 The heating temperature for the secondary firing is preferably 900° C. or lower, more preferably 850° C. or lower, because desorption of oxygen and volatilization of Li occur at a high temperature of 900° C. or higher. The heating time for the secondary firing can be appropriately set depending on the relationship with the heating temperature. For example, when the heating temperature is 780 to 850° C., it can be 4 to 12 hours.

本発明の実施形態に係る全固体リチウムイオン電池用正極活物質の製造方法では、上述のように、共沈法で得られたＮｉＣｏＭｎ系金属水酸化物を原料として、Ｌｉが、ＮｉＣｏＭｎ系金属水酸化物におけるＮｉ、Ｃｏ及びＭｎの合計モル比の２０％以下のモル比となるようにリチウム塩を添加し、８５０℃以上で一次焼成する。一次焼成の後、更に追加で、Ｌｉが、ＮｉＣｏＭｎ系金属水酸化物に対して添加したリチウム塩との合計で、ＮｉＣｏＭｎ系金属水酸化物におけるＮｉ、Ｃｏ及びＭｎの合計モル比と同じモル比となるようにリチウム塩を添加し、７８０℃以上で二次焼成する。このような二段階焼成により、単一相で高強度を有する正極活物質を作製することができる。 In the method for producing a positive electrode active material for an all-solid lithium ion battery according to the embodiment of the present invention, as described above, the NiCoMn-based metal hydroxide obtained by the coprecipitation method is used as a raw material, and Li is a NiCoMn-based metal water. Lithium salt is added so that the total molar ratio of Ni, Co and Mn in the oxide is 20% or less, and primary firing is performed at 850° C. or higher. After the primary firing, Li is added to the NiCoMn-based metal hydroxide in the same molar ratio as the total molar ratio of Ni, Co, and Mn in the NiCoMn-based metal hydroxide in total with the lithium salt added to the NiCoMn-based metal hydroxide. Lithium salt is added so that By such two-step firing, a positive electrode active material having a single phase and high strength can be produced.

本発明の実施形態に係る全固体リチウムイオン電池用正極活物質の製造方法では、Ｌｉを含有した層状酸化物より、Ｌｉをあまり含まない立方晶の方が粒成長が起こり易いことを利用して、一次焼成時に量論組成のＬｉに対し２割以下のＬｉを添加し８５０℃以上で焼成することで、粒子径の大きな立方晶酸化物が作製され、ここで成長した粒子を原料として残りのＬｉを添加し二次焼成を行っている。これにより、層状構造単一の正極活物質を得ることができる。また、単独のＮｉ酸化物、Ｍｎ酸化物及びＣｏ酸化物の混合粉を原料とした作製方法では、組成の不均一が起きる。これに対し、本発明の実施形態に係る正極活物質の製造方法では、共沈水酸化物原料について、Ｎｉ、Ｍｎ及びＣｏの遷移金属が一つの粒子に均一に混ざった状態となっているため、組成の不均一が起こらないという利点もある。 In the method for producing a positive electrode active material for an all-solid-state lithium ion battery according to the embodiment of the present invention, a cubic crystal that does not contain much Li is more prone to grain growth than a layered oxide containing Li. , By adding less than 20% of Li to the stoichiometric composition of Li at the time of primary firing and firing at 850 ° C. or higher, a cubic crystal oxide with a large particle size is produced, and the particles grown here are used as raw materials for the remaining Secondary firing is performed by adding Li. Thereby, a positive electrode active material having a single layered structure can be obtained. Also, in the manufacturing method using a mixed powder of single Ni oxide, Mn oxide and Co oxide as a raw material, non-uniformity in composition occurs. On the other hand, in the method for producing a positive electrode active material according to the embodiment of the present invention, the coprecipitated hydroxide raw material is in a state in which the transition metals of Ni, Mn and Co are uniformly mixed in one particle, There is also the advantage that non-uniformity of composition does not occur.

（全固体リチウムイオン電池用正極活物質を備えた全固体リチウムイオン電池）
本発明の実施形態に係る全固体リチウムイオン電池用正極活物質を用いて正極層を形成し、固体電解質層、当該正極層及び負極層を備えた全固体リチウムイオン電池を作製することができる。負極層は、リチウムイオン電池において負極活物質として使用されているものが使用できる。固体電解質層は、固体電解質からなり、硫化物系ガラスセラミックス固体電解質及び／又は硫化物系ガラス固体電解質からなるものが好ましい。 (All-solid-state lithium-ion battery with positive electrode active material for all-solid-state lithium-ion battery)
A positive electrode layer can be formed using the positive electrode active material for an all-solid-state lithium-ion battery according to the embodiment of the present invention, and an all-solid-state lithium-ion battery including a solid electrolyte layer, the positive electrode layer, and the negative electrode layer can be produced. For the negative electrode layer, those used as negative electrode active materials in lithium ion batteries can be used. The solid electrolyte layer is made of a solid electrolyte, preferably a sulfide-based glass-ceramic solid electrolyte and/or a sulfide-based glass solid electrolyte.

以下、本発明及びその利点をより良く理解するための実施例を提供するが、本発明はこれらの実施例に限られるものではない。 The following examples are provided for a better understanding of the invention and its advantages, but the invention is not limited to these examples.

以下に示すように、実施例１～８及び比較例１～８にてそれぞれ正極活物質を作製し、その平均粒子径Ｄ５０、粒子強度、粒子構造を測定し、さらに当該正極活物質を用いた全固体リチウムイオン電池の電池特性を測定した。また、誘導結合プラズマ発光分光分析装置（ＩＣＰ－ＯＥＳ）及びイオンクロマトグラフ法により、正極活物質のＬｉ、Ｎｉ、Ｍｎ、Ｃｏの含有量を測定した。その分析結果から、当該正極活物質をＬｉaＮｉbＣｏcＭｎdＯ2の組成で表した場合のa、ｂ、ｃ、ｄを求めた。 As shown below, positive electrode active materials were prepared in Examples 1 to 8 and Comparative Examples 1 to 8, respectively, and their average particle diameter D50, particle strength, and particle structure were measured, and the positive electrode active materials were used. Battery characteristics of all-solid-state lithium-ion batteries were measured. Also, the contents of Li, Ni, Mn, and Co in the positive electrode active material were measured by an inductively coupled plasma-optical emission spectrometer (ICP-OES) and ion chromatography. From the analysis results, a, b, c, and d when the positive electrode active material was represented by the composition of Li a Ni b Co c Mnd O 2 were determined.

（実施例１～８及び比較例１～８）
硫酸ニッケル、硫酸コバルトおよび硫酸マンガンの１．５ｍｏｌ／Ｌ水溶液をそれぞれ作製し、各水溶液を所定量秤量して、Ｎｉ：Ｃｏ：Ｍｎが表１のｍｏｌ％比となるように混合金属塩溶液を調整して、反応槽へ入れた。 (Examples 1 to 8 and Comparative Examples 1 to 8)
A 1.5 mol/L aqueous solution of nickel sulfate, cobalt sulfate, and manganese sulfate was prepared, and a predetermined amount of each aqueous solution was weighed, and a mixed metal salt solution was added so that the ratio of Ni:Co:Mn would be the mol % ratio shown in Table 1. It was conditioned and placed in the reactor.

次に、反応槽内の混合液のｐＨが１１．０±０．５及びアンモニウムイオン濃度が１０～２５ｇ／Ｌとなるように、アンモニア水と２０質量％の水酸化ナトリウム水溶液を前記反応槽内の混合液中に添加し、共沈法によってＮｉ－Ｃｏ－Ｍｎの複合水酸化物を共沈させた。 Next, ammonia water and a 20% by mass sodium hydroxide aqueous solution are added to the reaction vessel so that the pH of the mixed solution in the reaction vessel is 11.0 ± 0.5 and the ammonium ion concentration is 10 to 25 g / L. and coprecipitated Ni--Co--Mn composite hydroxide by a coprecipitation method.

また、反応で生成する共沈物の酸化を防止するために反応槽へ窒素ガスを導入した。反応槽へ導入するガスはヘリウム、ネオン、アルゴン、炭酸ガスなどの酸化を促進しないガスであれば、上記の窒素ガスに限らず使用することができる。 In addition, nitrogen gas was introduced into the reactor to prevent oxidation of the coprecipitate produced in the reaction. The gas to be introduced into the reaction tank is not limited to the above nitrogen gas, as long as it does not promote oxidation, such as helium, neon, argon, and carbon dioxide gas.

共沈した沈殿物を吸引・濾過した後、純水で水洗して、１２０℃、１２時間の乾燥をした。このようにして作製されたＮｉ－Ｃｏ－Ｍｎ複合水酸化物粒子の組成：ＮｉbＣｏcＭｎd（ＯＨ）2を測定した。 After the coprecipitated precipitate was sucked and filtered, it was washed with pure water and dried at 120° C. for 12 hours. The composition of the Ni--Co--Mn composite hydroxide particles thus produced: Ni b Co c Mn d (OH) 2 was measured.

次に、Ｎｉ－Ｃｏ－Ｍｎ複合水酸化物粒子に炭酸リチウムを添加した。このとき、炭酸リチウムは、Ｌｉが、Ｎｉ－Ｃｏ－Ｍｎ複合水酸化物粒子におけるＮｉ、Ｃｏ及びＭｎの合計モル比に対して表１の割合（％）のモル比となるように添加した。 Next, lithium carbonate was added to the Ni--Co--Mn composite hydroxide particles. At this time, lithium carbonate was added so that the molar ratio of Li to the total molar ratio of Ni, Co, and Mn in the Ni—Co—Mn composite hydroxide particles is the ratio (%) shown in Table 1.

次に、炭酸リチウムを添加したＮｉ－Ｃｏ－Ｍｎ複合水酸化物粒子を、表１に示す加熱温度にて１０時間、一次焼成を行った。 Next, the Ni—Co—Mn composite hydroxide particles to which lithium carbonate was added were subjected to primary firing at the heating temperature shown in Table 1 for 10 hours.

次に、一次焼成後に得られた粉体に、更に水酸化リチウムを添加した。このとき、水酸化リチウムは、Ｌｉが、Ｎｉ－Ｃｏ－Ｍｎ複合水酸化物粒子におけるＮｉ、Ｃｏ及びＭｎの合計モル比に対して表１の割合（％）のモル比となるように添加した。 Next, lithium hydroxide was further added to the powder obtained after the primary firing. At this time, lithium hydroxide was added so that the molar ratio of Li to the total molar ratio of Ni, Co and Mn in the Ni—Co—Mn composite hydroxide particles is the ratio (%) in Table 1. .

次に、炭酸リチウムを添加したＮｉ－Ｃｏ－Ｍｎ複合水酸化物粒子を、表１に示す加熱温度にて４時間、二次焼成を行った。このようにして、正極活物質を作製した。 Next, the Ni—Co—Mn composite hydroxide particles to which lithium carbonate was added were subjected to secondary firing at the heating temperature shown in Table 1 for 4 hours. Thus, a positive electrode active material was produced.

－正極活物質の構造－
層状岩塩構造となる空間群Ｒ３－ｍに帰属する単一相であるか否かは、以下のようにして粉末Ｘ線回折法に基づく公知の方法で解析及び同定した。すなわち、正極活物質のＸ線回折パターンにおいて、主に回折角（２θ）＝１８．７°付近の（００３）面、３６．６°付近の（１０１）面、３８．３°付近の（０１２）面、４４．４°付近の（１０４）面、４８．６°付近の（０１５）面、５８．６°付近の（１０７）面、６４．４°付近の（０１８）面、６４．８°付近の（１１０）面、及び６８．０°付近等に出現する（１１３）面の計９本の空間群Ｒ３－ｍに帰属する回折ピークを検出することによって、層状岩塩構造の存在を確認する。これらピークのみが観察されるか否かで、層状岩塩構造となる空間群Ｒ３－ｍに帰属する単一相であるかどうか判断した。 -Structure of positive electrode active material-
Whether or not it is a single phase belonging to the space group R3-m with a layered rock salt structure was analyzed and identified by a known method based on the powder X-ray diffraction method as follows. That is, in the X-ray diffraction pattern of the positive electrode active material, mainly the (003) plane near the diffraction angle (2θ) = 18.7°, the (101) plane near 36.6°, the (012) plane near 38.3° ) plane, (104) plane near 44.4°, (015) plane near 48.6°, (107) plane near 58.6°, (018) plane near 64.4°, 64.8 The existence of a layered rock salt structure is confirmed by detecting the diffraction peaks attributed to a total of nine space groups R3-m, the (110) plane near ° and the (113) plane appearing near 68.0 °. do. Whether or not only these peaks were observed was judged to be a single phase belonging to the space group R3-m having a layered rock salt structure.

－単粒子比率－
正極活物質の単粒子比率は、以下のようにして測定した。まず、乾式粒子画像分析装置：Ｍｏｒｐｈｏｌｏｇｉ Ｇ３（Ｍａｌｖｅｒｎ Ｐａｎａｌｙｔｉｃａｌ社製）にて、約１万個の粉体粒子を測定する。測定は、サンプルカートリッジに対象となる正極活物質の粉体粒子を投入し、ガラスプレート上に当該正極活物質の粉体粒子を分散させ、粒子の投影画像を撮影し、粉体粒子の２次元形状得た。得られた２次元形状の解析で、粒子の包絡度を以下のようにして計算した。
粒子の包絡度＝凸包周囲長／粒子の実際の周囲長
このときの粒子の包絡度が０．９８以上のものを単粒子と、その個数の割合を単粒子比率とした。 -Single particle ratio-
The single particle ratio of the positive electrode active material was measured as follows. First, about 10,000 powder particles are measured with a dry particle image analyzer: Morphologi G3 (manufactured by Malvern Panalytical). In the measurement, the powder particles of the positive electrode active material to be targeted are put into a sample cartridge, the powder particles of the positive electrode active material are dispersed on a glass plate, the projection image of the particles is taken, and the two-dimensional measurement of the powder particles is performed. got the shape. By analyzing the obtained two-dimensional shape, the enveloping degree of the particles was calculated as follows.
Particle envelopment=perimeter of convex hull/actual perimeter of particle At this time, particles with an envelopment of 0.98 or more were defined as single particles, and the ratio of the number of particles was defined as the single particle ratio.

－平均粒子径Ｄ５０－
正極活物質の平均粒子径Ｄ５０は、それぞれＭｉｃｒｏｔｒａｃ製ＭＴ３３００ＥＸIIにより測定した。 -Average particle size D50-
The average particle diameter D50 of the positive electrode active material was measured by MT3300EXII manufactured by Microtrac.

－粒子強度－
正極活物質の粒子強度は、島津製作所製微小圧縮試験機ＭＣＴ－２１１によって、以下のように測定した。まず、分散させた粉末サンプルを試料台に置いた。次に、顕微鏡で平均粒子径Ｄ５０サイズの２次粒子一粒の中心を狙い、２０μｍの径の圧子を負荷速度０．５３２ｍＮ／ｓｅｃで押し付け、破断した際の強度をＮ＝１０で測定し、その平均値を各サンプルの粒子強度とした。 -Particle strength-
The particle strength of the positive electrode active material was measured using a microcompression tester MCT-211 manufactured by Shimadzu Corporation as follows. First, the dispersed powder sample was placed on the sample stage. Next, aim at the center of one secondary particle with an average particle size of D50 size with a microscope, press an indenter with a diameter of 20 μm at a load rate of 0.532 mN / sec, and measure the strength at N = 10 when broken, The average value was taken as the particle strength of each sample.

上記実施例１～８及び比較例１～８に係る試験条件及び評価結果を表１に示す。 Table 1 shows the test conditions and evaluation results for Examples 1 to 8 and Comparative Examples 1 to 8.

Figure 0007198170000001
Figure 0007198170000001

（評価結果）
実施例１～８では、平均粒子径Ｄ５０が２μｍ以上であり、粒子強度が３００ＭＰａ以上であり、層状岩塩構造となる空間群Ｒ３－ｍに帰属する単一相であり、単粒子の比率が８０％以上である全固体リチウムイオン電池用正極活物質が得られた。
比較例１～８では、粒子強度が３００ＭＰａ未満の全固体リチウムイオン電池用正極活物質、または、単一相を有さない全固体リチウムイオン電池用正極活物質が得られた。 (Evaluation results)
In Examples 1 to 8, the average particle diameter D50 is 2 μm or more, the particle strength is 300 MPa or more, the single phase belongs to the space group R3-m with a layered rock salt structure, and the ratio of single particles is 80. % or more was obtained.
In Comparative Examples 1 to 8, a positive electrode active material for an all-solid lithium ion battery having a particle strength of less than 300 MPa or a positive electrode active material for an all-solid lithium ion battery without a single phase was obtained.

図３に、実施例１及び比較例１で得られた各正極活物質のＸＲＤチャートを示す。実施例１ではＮｉＯのピークが観察されず、比較例１では、ＮｉＯのピークが３７．５°、４３．５°、６３．５°付近に観察された。 FIG. 3 shows XRD charts of the positive electrode active materials obtained in Example 1 and Comparative Example 1. As shown in FIG. In Example 1, no NiO peaks were observed, and in Comparative Example 1, NiO peaks were observed near 37.5°, 43.5°, and 63.5°.

Claims (5)

組成式：ＬｉaＮｉbＣｏcＭｎdＯ2
（式中、１．０≦ａ≦１．１０、０．８≦ｂ≦０．９、０．０５≦ｃ≦０．１９、０．０１≦ｄ≦０．１、ｂ＋ｃ＋ｄ＝１である。）
で表され、
平均粒子径Ｄ５０が２μｍ以上であり、粒子強度が３００ＭＰａ以上であり、層状岩塩構造となる空間群Ｒ３－ｍに帰属する単一相であり、単粒子の比率が８０％以上である全固体リチウムイオン電池用正極活物質。 Composition formula : LiaNibCocMndO2 _
(wherein 1.0≦a≦1.10, 0.8≦b≦0.9, 0.05≦c≦0.19, 0.01≦d≦0.1, and b+c+d=1. )
is represented by
All-solid lithium having an average particle diameter D50 of 2 μm or more, a particle strength of 300 MPa or more, a single phase belonging to the space group R3-m having a layered rock salt structure, and a single particle ratio of 80% or more. Positive electrode active material for ion batteries. 前記平均粒子径Ｄ５０が２μｍ以上６μｍ以下で、且つ、粒子強度が３００ＭＰａ以上８００ＭＰａ以下である請求項１に記載の全固体リチウムイオン電池用正極活物質。 The positive electrode active material for an all solid lithium ion battery according to claim 1, wherein the average particle diameter D50 is 2 µm or more and 6 µm or less, and the particle strength is 300 MPa or more and 800 MPa or less. 共沈法で作製されたＮｉＣｏＭｎ系金属水酸化物を準備する工程１と、
Ｌｉが、前記ＮｉＣｏＭｎ系金属水酸化物におけるＮｉ、Ｃｏ及びＭｎの合計モル比の２０％以下のモル比となるように、前記ＮｉＣｏＭｎ系金属水酸化物にリチウム塩を添加し、８５０℃以上で一次焼成する工程２と、
前記一次焼成後に得られた粉体に、前記工程２で添加したリチウム塩との合計で、Ｌｉが、前記ＮｉＣｏＭｎ系金属水酸化物におけるＮｉ、Ｃｏ及びＭｎの合計モル比と同じモル比以上となるように、更にリチウム塩を添加し、７８０℃以上で二次焼成する工程３と、を含む請求項１または２に記載の全固体リチウムイオン電池用正極活物質の製造方法。 Step 1 of preparing a NiCoMn-based metal hydroxide produced by a coprecipitation method;
Lithium salt is added to the NiCoMn-based metal hydroxide so that the molar ratio of Li to the total molar ratio of Ni, Co and Mn in the NiCoMn-based metal hydroxide is 20% or less. Step 2 of primary firing;
The total molar ratio of Li to the powder obtained after the primary firing, together with the lithium salt added in step 2, is equal to or greater than the total molar ratio of Ni, Co, and Mn in the NiCoMn-based metal hydroxide. 3. The method for producing a positive electrode active material for an all-solid lithium ion battery according to claim 1 or 2, further comprising a step 3 of adding a lithium salt and secondary firing at 780° C. or higher so that the mixture becomes . 前記共沈法は、ニッケル塩、コバルト塩及びマンガン塩の混合物の水溶液に、アンモニア水及び水酸化ナトリウムを加えてＮｉＣｏＭｎ系金属水酸化物を得る方法である請求項３に記載の全固体リチウムイオン電池用正極活物質の製造方法。 The all-solid lithium ion according to claim 3, wherein the coprecipitation method is a method of adding ammonia water and sodium hydroxide to an aqueous solution of a mixture of nickel salt, cobalt salt and manganese salt to obtain a NiCoMn-based metal hydroxide. A method for producing a positive electrode active material for a battery. 正極層、負極層及び固体電解質層を備え、
請求項１または２に記載の全固体リチウムイオン電池用正極活物質を前記正極層に備えた全固体リチウムイオン電池。 A positive electrode layer, a negative electrode layer and a solid electrolyte layer,
An all-solid lithium ion battery comprising the positive electrode active material for an all-solid lithium ion battery according to claim 1 or 2 in the positive electrode layer.
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