JP6667985B2 - Lithium ion secondary battery - Google Patents

Lithium ion secondary battery Download PDF

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JP6667985B2
JP6667985B2 JP2014165428A JP2014165428A JP6667985B2 JP 6667985 B2 JP6667985 B2 JP 6667985B2 JP 2014165428 A JP2014165428 A JP 2014165428A JP 2014165428 A JP2014165428 A JP 2014165428A JP 6667985 B2 JP6667985 B2 JP 6667985B2
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JP2016042417A (en
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聡 藤木
聡 藤木
相原 雄一
雄一 相原
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Samsung Electronics Co Ltd
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    • HELECTRICITY
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    • HELECTRICITY
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    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/052Li-accumulators
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/056Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0561Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
    • H01M10/0562Solid materials
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    • H01M4/0402Methods of deposition of the material
    • H01M4/0404Methods of deposition of the material by coating on electrode collectors
    • HELECTRICITY
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    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/04Processes of manufacture in general
    • H01M4/0471Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/13Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139Processes of manufacture
    • H01M4/1391Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/48Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/50Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese
    • H01M4/505Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of manganese of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00Electrodes
    • H01M4/02Electrodes composed of, or comprising, active material
    • H01M4/36Selection of substances as active materials, active masses, active liquids
    • H01M4/48Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
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    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00Electrolytes
    • H01M2300/0017Non-aqueous electrolytes
    • H01M2300/0065Solid electrolytes
    • H01M2300/0068Solid electrolytes inorganic
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50Manufacturing or production processes characterised by the final manufactured product

Description

本発明は、リチウムイオン二次電池に関する。   The present invention relates to a lithium ion secondary battery.

リチウムイオン二次電池は、大きな充放電容量、高い作動電位、優れた充放電サイクル(cycle)特性を有するため、携帯情報端末、携帯電子機器、家庭用小型電力貯蔵装置、モーター(motor)を動力源とする自動二輪車、電気自動車、ハイブリッド(hybrid)電気自動車等の用途への需要が増大している。リチウムイオン二次電池では、電解質として、有機溶媒にリチウム塩を溶解させた非水電解液が用いられているが、このような非水電解液は、その発火のし易さや電解液の漏れ等の問題から、安全性が懸念されている。そのため、近年、リチウムイオン二次電池の安全性の向上を目的として、不燃材料である無機材料からなる固体電解質を用いた全固体型リチウムイオン二次電池の研究が盛んに行われている。   Lithium ion secondary batteries have large charge / discharge capacities, high operating potentials, and excellent charge / discharge cycle characteristics, so that portable information terminals, portable electronic devices, household small power storage devices, and motors can be powered. There is an increasing demand for applications such as motorcycles, electric vehicles, and hybrid electric vehicles as a source. In a lithium ion secondary battery, a non-aqueous electrolyte in which a lithium salt is dissolved in an organic solvent is used as an electrolyte. However, such a non-aqueous electrolyte is apt to ignite or leak electrolyte. Due to the above problems, safety is a concern. Therefore, in recent years, all-solid-state lithium ion secondary batteries using a solid electrolyte made of an inorganic material, which is a non-combustible material, have been actively studied for the purpose of improving the safety of the lithium ion secondary batteries.

全固体型リチウムイオン二次電池の固体電解質としては硫化物や酸化物等を使用できるが、リチウムイオン伝導性の観点から硫化物系の固体電解質が最も期待できる材料である。ところが、硫化物系の固体電解質を使用した場合には、充電の際に正極活物質粒子と固体電解質粒子との界面で反応が起こり、この界面に抵抗成分が生成することにより、正極活物質粒子と固体電解質粒子との界面をリチウムイオンが移動する際の抵抗(以下、「界面抵抗」とも称する。)が増大しやすくなる。この界面抵抗の増大により、リチウムイオン伝導性が低下するため、全固体型リチウムイオン二次電池の出力が低下する、という問題があった。   As the solid electrolyte of the all-solid-state lithium ion secondary battery, sulfide, oxide, or the like can be used, but from the viewpoint of lithium ion conductivity, a sulfide-based solid electrolyte is the most promising material. However, when a sulfide-based solid electrolyte is used, a reaction occurs at the interface between the positive electrode active material particles and the solid electrolyte particles during charging, and a resistance component is generated at this interface. (Hereinafter, also referred to as “interface resistance”) when lithium ions move at the interface between the particles and the solid electrolyte particles. Due to the increase in the interface resistance, the lithium ion conductivity is reduced, so that there is a problem that the output of the all solid-state lithium ion secondary battery is reduced.

このような問題に対して、LiCoO(以下、「LCO」とも称する。)等の正極活物質粒子の表面をリチウムイオン導電層で被覆することが検討されている。例えば、特許文献1や特許文献2では、正極活物質粒子の表面をLiNbO、LiTi12やAl化合物などで被覆することが報告されている。 To cope with such a problem, it has been studied to coat the surface of positive electrode active material particles such as LiCoO 2 (hereinafter also referred to as “LCO”) with a lithium ion conductive layer. For example, Patent Documents 1 and 2 report that the surface of the positive electrode active material particles is coated with LiNbO 3 , Li 4 Ti 5 O 12 , an Al compound, or the like.

特開2010−192373号公報JP 2010-192373 A 特許第4982866号Patent No. 498866

しかし、上記の技術では、全固体型リチウムイオン二次電池の出力、特に放電容量及びサイクル特性について満足な値を得ることができなかった。そこで、本発明は、上記問題に鑑みてなされたものであり、本発明の目的とするところは、全固体型リチウムイオン二次電池の放電容量及びサイクル特性を改善することが可能な、新規かつ改良されたリチウムイオン二次電池を提供することにある。   However, according to the above-mentioned technology, satisfactory values cannot be obtained for the output of the all-solid-state lithium ion secondary battery, particularly for the discharge capacity and cycle characteristics. Therefore, the present invention has been made in view of the above-described problems, and an object of the present invention is to provide a novel and solid-state lithium ion secondary battery capable of improving the discharge capacity and cycle characteristics. An object of the present invention is to provide an improved lithium ion secondary battery.

上記課題を解決するために、本発明のある観点によれば、複数の正極活物質一次粒子が凝集した正極活物質二次粒子、及び正極活物質二次粒子の表面の少なくとも一部を覆う被覆層を備える被覆粒子と、被覆粒子に接触する固体電解質粒子と、を備え、正極活物質二次粒子の平均粒径は、3.0〜10.0μmであり、被覆層は、ニッケルとは異なる元素Xを含有し、かつ、非晶質であり、被覆層に含まれる元素Xと正極活物質二次粒子内のリチウム以外の全金属元素とのモル比が0.1〜10.0mol%であることを特徴とする、リチウムイオン二次電池が提供される。   In order to solve the above-described problems, according to an aspect of the present invention, a plurality of positive electrode active material primary particles are aggregated into a positive electrode active material secondary particle, and a coating covering at least a part of the surface of the positive electrode active material secondary particle. A coating particle having a layer, and solid electrolyte particles in contact with the coating particles, wherein the secondary particles of the positive electrode active material have an average particle size of 3.0 to 10.0 μm, and the coating layer is different from nickel. The molar ratio of the element X contained in the coating layer and amorphous, and the total metal element other than lithium in the secondary particles of the positive electrode active material is 0.1 to 10.0 mol%. A lithium ion secondary battery is provided.

この観点によれば、全固体型リチウムイオン二次電池の放電容量及びサイクル特性が改善される。   According to this viewpoint, the discharge capacity and cycle characteristics of the all solid-state lithium ion secondary battery are improved.

ここで、被覆層は、リチウムを含んでいてもよい。   Here, the coating layer may contain lithium.

この観点によれば、全固体型リチウムイオン二次電池の放電容量及びサイクル特性が改善される。   According to this viewpoint, the discharge capacity and cycle characteristics of the all solid-state lithium ion secondary battery are improved.

また、正極活物質二次粒子は、以下の化学式1で示される正極活物質、及び以下の化学式2で示される正極活物質のうち、少なくとも一方を含んでいてもよい。
LiNi1−y (1)
化学式1において、MはCo、Mn、AlおよびMgからなる群から選ばれる1種以上の元素であり、x、yは、0.5<x<1.4、0.3<yを満たす値である。
LiNi2−y (2)
化学式2において、MはCoおよびMnからなる群から選ばれる1種以上の元素であり、x、yは、0.5<x<1.1、0.3<yを満たす値である。
Further, the positive electrode active material secondary particles may include at least one of a positive electrode active material represented by the following chemical formula 1 and a positive electrode active material represented by the following chemical formula 2.
Li x Ni y M 1-y O 2 (1)
In Chemical Formula 1, M is at least one element selected from the group consisting of Co, Mn, Al and Mg, and x and y are values satisfying 0.5 <x <1.4 and 0.3 <y. It is.
Li x Ni y M 2-y O 4 (2)
In Chemical Formula 2, M is at least one element selected from the group consisting of Co and Mn, and x and y are values satisfying 0.5 <x <1.1 and 0.3 <y.

この観点によれば、全固体型リチウムイオン二次電池の放電容量及びサイクル特性が改善される。   According to this viewpoint, the discharge capacity and cycle characteristics of the all solid-state lithium ion secondary battery are improved.

また、元素Xは、金属元素及び半金属元素のうち少なくとも1種であってもよい。   The element X may be at least one of a metal element and a metalloid element.

この観点によれば、全固体型リチウムイオン二次電池の放電容量及びサイクル特性が改善される。   According to this viewpoint, the discharge capacity and cycle characteristics of the all solid-state lithium ion secondary battery are improved.

また、元素Xは、Y,La,Ce,Nd,Sm,Eu,Ti,Zr,V,Nb,Cr,Mn,Fe,Co,Cu,Zn,Al,Si,Ga、Ge,及びInからなる群から選択される少なくとも1種であってもよい。   The element X is composed of Y, La, Ce, Nd, Sm, Eu, Ti, Zr, V, Nb, Cr, Mn, Fe, Co, Cu, Zn, Al, Si, Ga, Ge, and In. At least one member selected from the group may be used.

この観点によれば、全固体型リチウムイオン二次電池の放電容量及びサイクル特性が改善される。   According to this viewpoint, the discharge capacity and cycle characteristics of the all solid-state lithium ion secondary battery are improved.

また、固体電解質粒子は、硫化物系固体電解質粒子であってもよい。   Further, the solid electrolyte particles may be sulfide-based solid electrolyte particles.

この観点によれば、全固体型リチウムイオン二次電池の放電容量及びサイクル特性が改善される。   According to this viewpoint, the discharge capacity and cycle characteristics of the all solid-state lithium ion secondary battery are improved.

また、硫化物系固体電解質粒子は、ケイ素、リン、及びホウ素からなる群から選ばれる一種以上の元素を含有していてもよい。   Further, the sulfide-based solid electrolyte particles may contain one or more elements selected from the group consisting of silicon, phosphorus, and boron.

この観点によれば、全固体型リチウムイオン二次電池の放電容量及びサイクル特性が改善される。   According to this viewpoint, the discharge capacity and cycle characteristics of the all solid-state lithium ion secondary battery are improved.

以上説明したように本発明によれば、この観点によれば、全固体型リチウムイオン二次電池の放電容量及びサイクル特性が改善される。   As described above, according to the present invention, from this viewpoint, the discharge capacity and cycle characteristics of the all-solid-state lithium ion secondary battery are improved.

本発明の好適な実施形態に係るリチウムイオン二次電池の構成を模式的に示す説明図である。FIG. 1 is an explanatory diagram schematically showing a configuration of a lithium ion secondary battery according to a preferred embodiment of the present invention. 本実施形態に係る被覆粒子の構成を模式的に示す説明図である。FIG. 3 is an explanatory view schematically showing a configuration of a coated particle according to the embodiment. 従来の全固体型リチウムイオン二次電池における界面抵抗の増大の様子を示す説明図である。FIG. 9 is an explanatory diagram showing how an interface resistance increases in a conventional all solid-state lithium ion secondary battery. 従来の正極活物質粒子の構成を示す説明図である。FIG. 3 is an explanatory view showing a configuration of a conventional positive electrode active material particle.

以下に添付図面を参照しながら、本発明の好適な実施の形態について詳細に説明する。なお、本明細書及び図面において、実質的に同一の機能構成を有する構成要素については、同一の符号を付することにより重複説明を省略する。   Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the specification and the drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

<1.固体電解質を用いた場合の問題点>
まず、図3に基づいて、固体電解質を用いた場合の問題点について説明する。図3は、従来の全固体型リチウムイオン二次電池100(以下、「リチウムイオン二次電池100」とも称する)の概略構成を示す説明図である。
<1. Problems when using solid electrolyte>
First, a problem when a solid electrolyte is used will be described with reference to FIG. FIG. 3 is an explanatory diagram showing a schematic configuration of a conventional all-solid-state lithium ion secondary battery 100 (hereinafter, also referred to as “lithium ion secondary battery 100”).

リチウムイオン二次電池100は、正極層110、負極層120、及び固体電解質層130が積層された構造を有する。正極層110は、正極活物質粒子111と硫化物系固体電解質粒子131(以下、「固体電解質粒子131」とも称する)とを混合した混合粒子で構成される。同様に、負極層120は、負極活物質粒子121と固体電解質粒子131とを混合した混合粒子で構成される。固体電解質層130は、正極層110と負極層120との間に設けられる。固体電解質層130は、固体電解質粒子131で構成される。   The lithium ion secondary battery 100 has a structure in which a positive electrode layer 110, a negative electrode layer 120, and a solid electrolyte layer 130 are stacked. The positive electrode layer 110 is composed of mixed particles obtained by mixing the positive electrode active material particles 111 and sulfide-based solid electrolyte particles 131 (hereinafter, also referred to as “solid electrolyte particles 131”). Similarly, the negative electrode layer 120 is composed of mixed particles obtained by mixing the negative electrode active material particles 121 and the solid electrolyte particles 131. The solid electrolyte layer 130 is provided between the positive electrode layer 110 and the negative electrode layer 120. The solid electrolyte layer 130 is composed of solid electrolyte particles 131.

硫化物系固体電解質を用いたリチウムイオン二次電池100では、正極活物質及び電解質が固体であるため、電解質として有機電解液を用いた場合よりも電解質が正極活物質の内部へ浸透しにくく、正極活物質と電解質との界面の面積が減少しやすいことから、リチウムイオン及び電子の移動経路を十分に確保することが困難である。そのため、図3に示すように、正極活物質粒子111と硫化物系固体電解質粒子131とを混合した混合粒子で正極層110を構成し、負極活物質粒子121と硫化物系固体電解質粒子131とを混合した混合粒子で負極層120を構成するようにしている。これにより、活物質と固体電解質との界面の面積を増大させている。   In the lithium ion secondary battery 100 using a sulfide-based solid electrolyte, since the positive electrode active material and the electrolyte are solid, the electrolyte is less likely to penetrate into the positive electrode active material than when an organic electrolyte is used as the electrolyte, Since the area of the interface between the positive electrode active material and the electrolyte tends to decrease, it is difficult to secure a sufficient migration path for lithium ions and electrons. Therefore, as shown in FIG. 3, the positive electrode layer 110 is composed of mixed particles obtained by mixing the positive electrode active material particles 111 and the sulfide-based solid electrolyte particles 131, and the negative electrode active material particles 121 and the sulfide-based solid electrolyte particles 131 The negative electrode layer 120 is constituted by the mixed particles obtained by mixing. Thereby, the area of the interface between the active material and the solid electrolyte is increased.

しかしながら、上述したように、充電の際に正極活物質粒子111と固体電解質粒子131との界面で反応が起こり、高抵抗層150が形成される。具体的には、高抵抗層150は、正極活物質粒子111の表面に存在する遷移金属元素及び酸素(元素)と固体電解質粒子131の表面に存在する硫黄元素との反応(副反応)によって生成される。ここで、「高抵抗層150」とは、正極活物質粒子111と固体電解質粒子131との界面に形成される抵抗成分からなる層であって、正極活物質粒子111の内部や硫化物系固体電解質粒子131よりも、リチウムイオンが移動する際の抵抗が大きくなる層を意味する。このため、正極活物質粒子111と固体電解質粒子131との界面抵抗が増大しやすくなる。そして、正極活物質粒子111と固体電解質粒子131との界面の面積を増大させると、リチウムイオン及び電子の移動経路を確保することができる反面、高抵抗層150が形成されやすくなる。このため、正極活物質粒子111から固体電解質粒子131へのリチウムイオンの移動が高抵抗層150により阻害される。この結果、リチウムイオン伝導性が低下するため、リチウムイオン二次電池100の出力が低下する。   However, as described above, a reaction occurs at the interface between the positive electrode active material particles 111 and the solid electrolyte particles 131 during charging, and the high resistance layer 150 is formed. Specifically, the high resistance layer 150 is generated by a reaction (side reaction) between a transition metal element and oxygen (element) existing on the surface of the positive electrode active material particles 111 and a sulfur element existing on the surface of the solid electrolyte particles 131. Is done. Here, the “high resistance layer 150” is a layer formed of a resistance component formed at the interface between the positive electrode active material particles 111 and the solid electrolyte particles 131, and includes the inside of the positive electrode active material particles 111 and a sulfide-based solid. It means a layer in which resistance when lithium ions move is larger than that of the electrolyte particles 131. Therefore, the interface resistance between the positive electrode active material particles 111 and the solid electrolyte particles 131 tends to increase. When the area of the interface between the positive electrode active material particles 111 and the solid electrolyte particles 131 is increased, the movement paths of lithium ions and electrons can be secured, but the high resistance layer 150 is easily formed. Therefore, movement of lithium ions from the positive electrode active material particles 111 to the solid electrolyte particles 131 is inhibited by the high resistance layer 150. As a result, the lithium ion conductivity decreases, and the output of the lithium ion secondary battery 100 decreases.

上記非特許文献1〜2には、上記問題点を解決することを目的とした技術として、正極活物質の表面をLiNbO、LiTi12やAl化合物などで被覆することが開示されている。しかし、本発明者がこれらの技術について詳細に検討したところ、これらの技術では、依然として全固体型リチウムイオン二次電池の出力、特に放電容量及びサイクル特性について満足な値を得ることができなかった。 Non-Patent Documents 1 and 2 disclose that the surface of a positive electrode active material is coated with LiNbO 3 , Li 4 Ti 5 O 12 , an Al compound, or the like, as a technique for solving the above problems. ing. However, when the present inventor studied these techniques in detail, they could not still obtain satisfactory values for the output of the all-solid-state lithium-ion secondary battery, particularly for the discharge capacity and cycle characteristics. .

<2.本発明者による検討>
そこで、本発明者は、全固体型リチウムイオン二次電池100の出力に影響を与える要因が上記の高抵抗層150以外にも存在するのではないかと考えた。そして、本発明者は、正極活物質粒子111の構造に着目した。図4に示すように、正極活物質粒子111は、複数の正極活物質一次粒子111aが凝集した正極活物質二次粒子として存在する。そして、固体電解質粒子131は、正極活物質粒子111の表面に接触することはできるが、正極活物質一次粒子111a間の隙間には入り込めない。したがって、正極活物質粒子111と固体電解質粒子131との間でのリチウムイオンのやりとりは、正極活物質粒子111の表面で行われる。このため、充電時にリチウムイオンが正極活物質粒子111の全域に行き渡るまでの時間、いわゆる拡散時間は、正極活物質粒子111の粒径(いわゆる二次粒径)に依存する。本発明者は、拡散時間、すなわち、正極活物質粒子111の粒径がリチウムイオン二次電池100の出力に影響を与えているのではないかと考えた。
<2. Study by the Inventor>
Therefore, the present inventor has considered that factors affecting the output of the all-solid-state lithium-ion secondary battery 100 may be present in addition to the high-resistance layer 150. Then, the present inventors paid attention to the structure of the positive electrode active material particles 111. As shown in FIG. 4, the positive electrode active material particles 111 exist as positive electrode active material secondary particles in which a plurality of positive electrode active material primary particles 111a are aggregated. The solid electrolyte particles 131 can come into contact with the surface of the positive electrode active material particles 111, but cannot enter the gaps between the positive electrode active material primary particles 111a. Therefore, exchange of lithium ions between the positive electrode active material particles 111 and the solid electrolyte particles 131 is performed on the surface of the positive electrode active material particles 111. Therefore, the time required for lithium ions to reach the entire area of the positive electrode active material particles 111 during charging, that is, the diffusion time, depends on the particle size of the positive electrode active material particles 111 (so-called secondary particle size). The present inventor has considered that the diffusion time, that is, the particle size of the positive electrode active material particles 111 may affect the output of the lithium ion secondary battery 100.

さらに、本発明者は、上述した副反応を抑制するための被覆層にも着目し、被覆層の組成もリチウムイオン二次電池100の出力に影響を与えるのではないかと考えた。そこで、本発明者は、正極活物質粒子の粒径、被覆層の組成を変更しながら全固体型リチウムイオン二次電池の出力を測定したところ、正極活物質粒子の粒径、被覆層の組成が所定の条件を満たす場合に、全固体型リチウムイオン二次電池の出力が顕著に改善されることを見出した。そして、本発明者は、上記の知見に基づいて、本実施形態に係るリチウムイオン二次電池に想到するに至った。以下、本実施形態に係るリチウムイオン二次電池について詳細に説明する。   Furthermore, the present inventor paid attention to the coating layer for suppressing the side reaction described above, and thought that the composition of the coating layer might affect the output of the lithium ion secondary battery 100. Thus, the present inventor measured the output of the all-solid-state lithium ion secondary battery while changing the particle size of the positive electrode active material particles and the composition of the coating layer. Found that the output of the all-solid-state lithium-ion secondary battery was significantly improved when satisfies a predetermined condition. Then, based on the above findings, the present inventor has come to the lithium ion secondary battery according to the present embodiment. Hereinafter, the lithium ion secondary battery according to the present embodiment will be described in detail.

<3.リチウムイオン二次電池の構成>
続いて、図1を参照しながら、本発明の好適な実施形態に係るリチウムイオン二次電池の構成について詳細に説明する。図1は、本実施形態に係るリチウムイオン二次電池1の構成を模式的に示す説明図である。
<3. Configuration of lithium ion secondary battery>
Subsequently, the configuration of the lithium ion secondary battery according to a preferred embodiment of the present invention will be described in detail with reference to FIG. FIG. 1 is an explanatory diagram schematically showing the configuration of the lithium ion secondary battery 1 according to the present embodiment.

図1に示すように、本実施形態に係るリチウムイオン二次電池1は、全固体型リチウムイオン二次電池であり、正極層10と、負極層20と、正極層10及び負極層20の間に設けられる固体電解質層30とが積層された構造を有する。   As shown in FIG. 1, the lithium ion secondary battery 1 according to the present embodiment is an all solid-state lithium ion secondary battery, and includes a positive electrode layer 10, a negative electrode layer 20, and a positive electrode layer 10 and a negative electrode layer 20. Has a structure in which the solid electrolyte layer 30 is laminated.

(2.1.正極層10)
正極層10は、被覆粒子10aと固体電解質粒子31とを混合した混合粒子を含む。被覆粒子10aは、正極活物質粒子11と、正極活物質粒子11の表面を覆う被覆層12とを有する。したがって、被覆層12が固体電解質粒子31に接触する。上述したように、固体電解質粒子131を使用したリチウムイオン二次電池100は、正極活物質粒子111と固体電解質粒子131との界面での反応により界面抵抗が上昇し、電池の出力が低下するという問題がある。しかし、本実施形態に係る全固体型のリチウムイオン二次電池1によれば、正極活物質粒子11の表面が特定の組成及び層厚を有する被覆層12で被覆されている。さらに、正極活物質粒子11の粒径(二次粒径)は特定の範囲内の値となっている。このため、固体電解質粒子31中の硫黄元素と正極活物質粒子11中の遷移金属元素との反応(副反応)が抑制され、かつ、リチウムイオン二次電池1の出力が向上する。
(2.1. Positive electrode layer 10)
Positive electrode layer 10 includes mixed particles obtained by mixing coating particles 10 a and solid electrolyte particles 31. The coating particles 10 a include the positive electrode active material particles 11 and a coating layer 12 that covers the surface of the positive electrode active material particles 11. Therefore, the coating layer 12 comes into contact with the solid electrolyte particles 31. As described above, in the lithium ion secondary battery 100 using the solid electrolyte particles 131, the interface resistance increases due to the reaction at the interface between the positive electrode active material particles 111 and the solid electrolyte particles 131, and the output of the battery decreases. There's a problem. However, in the all-solid-state lithium ion secondary battery 1 according to the present embodiment, the surface of the positive electrode active material particles 11 is covered with the coating layer 12 having a specific composition and a layer thickness. Further, the particle size (secondary particle size) of the positive electrode active material particles 11 is a value within a specific range. Therefore, the reaction (side reaction) between the sulfur element in the solid electrolyte particles 31 and the transition metal element in the positive electrode active material particles 11 is suppressed, and the output of the lithium ion secondary battery 1 is improved.

なお、正極活物質粒子11は、その表面の少なくとも一部が被覆層12で被覆されていればよい。すなわち、正極活物質粒子11の表面全体が被覆層12で被覆されていてもよく、正極活物質粒子11の表面が部分的に被覆層12で被覆されていてもよい。   Note that the positive electrode active material particles 11 only need to have at least a part of their surfaces covered with the coating layer 12. That is, the entire surface of the positive electrode active material particles 11 may be covered with the coating layer 12, or the surface of the positive electrode active material particles 11 may be partially covered with the coating layer 12.

また、正極活物質粒子11の粒子表面に被覆層12が形成されていることは、例えば、正極活物質粒子11と被覆層12との構造上の差異に起因するコントラストの違いを利用した、顕微鏡画像(電界放出形走査電子顕微鏡(FE−SEM)や透過型電子顕微鏡(TEM)の画像)解析等の方法により確認することができる。以下、正極層10に含まれる正極活物質粒子11及び被覆層12について詳述する。   Further, the fact that the coating layer 12 is formed on the particle surface of the positive electrode active material particles 11 can be achieved, for example, by using a microscope that utilizes a difference in contrast caused by a structural difference between the positive electrode active material particles 11 and the coating layer 12. It can be confirmed by a method such as image analysis (image of a field emission scanning electron microscope (FE-SEM) or a transmission electron microscope (TEM)). Hereinafter, the positive electrode active material particles 11 and the coating layer 12 included in the positive electrode layer 10 will be described in detail.

(正極活物質粒子11)
正極活物質粒子11は、図2に示すように、複数の正極活物質一次粒子11aが凝集した正極活物質二次粒子として存在する。そして、正極活物質粒子11の平均粒径(二次粒子の平均粒径)は、3.0〜10.0μmである。ここで、正極活物質粒子11の粒径は、正極活物質粒子11を球体とみなした場合の粒径である。また、平均粒径は、正極活物質粒子11の粒径のD50(メジアン径)である。正極活物質粒子11の平均粒径がこの範囲内の値となる場合に、リチウムイオン二次電池1の出力が大きく向上する。なお、正極活物質粒子11の平均粒径が3μm未満となる場合、リチウムイオン二次電池1の出力、特に放電容量が低下する。この理由としては、固体電解質粒子31に接触できない正極活物質粒子11が増加することが考えられる。一方、正極活物質粒子11の平均粒径が10μmを超える場合、リチウムイオン二次電池1の出力が低下する。この理由としては、上述した拡散時間が長くなり過ぎることが考えられる。
(Positive electrode active material particles 11)
As shown in FIG. 2, the positive electrode active material particles 11 exist as positive electrode active material secondary particles in which a plurality of positive electrode active material primary particles 11a are aggregated. The average particle size of the positive electrode active material particles 11 (the average particle size of the secondary particles) is 3.0 to 10.0 μm. Here, the particle size of the positive electrode active material particles 11 is a particle size when the positive electrode active material particles 11 are regarded as a sphere. The average particle diameter is D50 (median diameter) of the particle diameter of the positive electrode active material particles 11. When the average particle size of the positive electrode active material particles 11 falls within this range, the output of the lithium ion secondary battery 1 is greatly improved. When the average particle size of the positive electrode active material particles 11 is less than 3 μm, the output of the lithium ion secondary battery 1, particularly, the discharge capacity decreases. This may be because the number of the positive electrode active material particles 11 that cannot contact the solid electrolyte particles 31 increases. On the other hand, when the average particle diameter of the positive electrode active material particles 11 exceeds 10 μm, the output of the lithium ion secondary battery 1 decreases. The reason may be that the above diffusion time is too long.

ここで、正極活物質粒子11の平均粒径は、レーザ回折・散乱式粒子径分布測定装置(例えば、日機装株式会社製マイクロトラックMT−3000II)によって測定可能である。   Here, the average particle size of the positive electrode active material particles 11 can be measured by a laser diffraction / scattering type particle size distribution measuring device (for example, Microtrack MT-3000II manufactured by Nikkiso Co., Ltd.).

正極活物質粒子11を構成する正極活物質としては、リチウムイオンを可逆的に吸蔵及び放出することが可能な物質であれば特に限定されず、例えば、コバルト酸リチウム(LCO)、ニッケル酸リチウム、ニッケルコバルト酸リチウム、ニッケルマンガン酸リチウム、ニッケルコバルトアルミニウム酸リチウム(以下、「NCA」と称する場合もある。)、ニッケルコバルトマンガン酸リチウム(以下、「NCM」と称する場合もある。)、マンガン酸リチウム、リン酸鉄リチウム、硫化ニッケル、硫化銅、硫黄、酸化鉄、酸化バナジウム等が挙げられる。これらの正極活物質は、単独で用いられてもよく、2種以上が併用されてもよい。   The positive electrode active material constituting the positive electrode active material particles 11 is not particularly limited as long as it can reversibly occlude and release lithium ions. For example, lithium cobaltate (LCO), lithium nickelate, Lithium nickel cobaltate, lithium nickel manganate, lithium nickel cobalt aluminate (hereinafter sometimes referred to as “NCA”), lithium nickel cobalt manganate (hereinafter sometimes referred to as “NCM”), manganic acid Examples include lithium, lithium iron phosphate, nickel sulfide, copper sulfide, sulfur, iron oxide, and vanadium oxide. These positive electrode active materials may be used alone or in combination of two or more.

より具体的には、正極活物質粒子11は、以下の化学式1で示される正極活物質、及び以下の化学式2で示される正極活物質のうち、少なくとも一方を含むことが好ましい。正極活物質粒子11は、これらの正極活物質のうち、少なくとも一方で構成されることが好ましい。
LiNi1−y (1)
化学式1において、MはCo、Mn、AlおよびMgからなる群から選ばれる1種以上の元素であり、x、yは、0.5<x<1.4、0.3<yを満たす値である。
LiNi2−y (2)
化学式2において、MはCoおよびMnからなる群から選ばれる1種以上の元素であり、x、yは、0.5<x<1.1、0.3<yを満たす値である。
More specifically, the positive electrode active material particles 11 preferably include at least one of a positive electrode active material represented by the following chemical formula 1 and a positive electrode active material represented by the following chemical formula 2. The positive electrode active material particles 11 are preferably formed of at least one of these positive electrode active materials.
Li x Ni y M 1-y O 2 (1)
In Chemical Formula 1, M is at least one element selected from the group consisting of Co, Mn, Al and Mg, and x and y are values satisfying 0.5 <x <1.4 and 0.3 <y. It is.
Li x Ni y M 2-y O 4 (2)
In Chemical Formula 2, M is at least one element selected from the group consisting of Co and Mn, and x and y are values satisfying 0.5 <x <1.1 and 0.3 <y.

化学式1で示される正極活物質の例としては、LiNi0.8Co0.15Al0.05、LiNi1/3Co1/3Mn1/32、LiNi0.5Co0.2Mn0.3、LiNi0.8Co0.1Mn0.1等が挙げられる。なお、化学式1の組成を有しないが、本実施形態に適用可能な正極活物質として、Li1.15(Ni0.2Co0.2Mn0.60.85も挙げられる。化学式2で示される正極活物質の例としては、LiNi0.5Mn1.5等が挙げられる。 Examples of the positive electrode active material represented by Chemical Formula 1 include LiNi 0.8 Co 0.15 Al 0.05 O 2 , LiNi 1/3 Co 1/3 Mn 1/3 O 2, and LiNi 0.5 Co 0. 2 Mn 0.3 O 2 , LiNi 0.8 Co 0.1 Mn 0.1 O 2 and the like. Although not having the composition of Chemical Formula 1, Li 1.15 (Ni 0.2 Co 0.2 Mn 0.6 ) 0.85 O 2 can also be used as a positive electrode active material applicable to the present embodiment. Examples of the positive electrode active material represented by Chemical Formula 2 include LiNi 0.5 Mn 1.5 O 4 .

このように、本実施形態では、正極活物質粒子11は、ニッケルを多く含む(y>0.3)ことが好ましい。ニッケルを多く含む正極活物質粒子11は、リチウムイオン二次電池1の放電容量を大きくすることができる。その反面、ニッケルを多く含む正極活物質粒子11は、正極活物質粒子11内のリチウムイオンの拡散速度が遅い(例えば、コバルト酸リチウムよりも拡散速度が2桁程度遅い)ので、サイクル特性が低くなりやすい。しかし、本実施形態のように正極活物質粒子11の平均粒径を適切な範囲に調整することで、放電容量及びサイクル特性が向上する。   Thus, in the present embodiment, it is preferable that the positive electrode active material particles 11 contain a large amount of nickel (y> 0.3). The positive electrode active material particles 11 containing a large amount of nickel can increase the discharge capacity of the lithium ion secondary battery 1. On the other hand, the positive electrode active material particles 11 containing a large amount of nickel have low cycle characteristics because the diffusion rate of lithium ions in the positive electrode active material particles 11 is slow (for example, the diffusion speed is about two orders of magnitude slower than that of lithium cobalt oxide). Prone. However, by adjusting the average particle diameter of the positive electrode active material particles 11 to an appropriate range as in the present embodiment, the discharge capacity and the cycle characteristics are improved.

化学式1、2で表される正極活物質のうち、特に好ましいのは、NCA、NCMである。これらは層状岩塩型構造を有する。ここでいう「層状」とは、薄いシート状の形状のことを意味し、「岩塩型構造」とは、結晶構造の1種である塩化ナトリウム型構造のことであり、陽イオン及び陰イオンのそれぞれが形成する面心立方格子が、互いに単位格子の稜の1/2だけずれた構造を指す。NCAやNCMで構成される正極活物質粒子11は、LCO等の粒子よりも粒径が小さく、比表面積が大きい(約10倍)。したがって、正極活物質粒子11と固体電解質粒子31との接触面積が大きくなり、リチウムイオン伝導性が向上するため、電池の出力が上昇する。また、正極活物質粒子11の構成元素としてニッケルを含むことにより、リチウムイオン二次電池1の容量密度を上昇させ、また、充電状態での金属溶出が少ないため充電状態でのリチウムイオン二次電池1の長期信頼性を向上させることができる。   Among the positive electrode active materials represented by Chemical Formulas 1 and 2, particularly preferred are NCA and NCM. These have a layered rock-salt type structure. The term “layered” as used herein means a thin sheet-like shape, and the term “rock salt type structure” refers to a sodium chloride type structure, which is a kind of crystal structure, and includes a cation and an anion. A face-centered cubic lattice formed by each of them indicates a structure shifted from each other by だ け of a ridge of a unit lattice. The positive electrode active material particles 11 composed of NCA or NCM have a smaller particle size and a larger specific surface area (about 10 times) than particles such as LCO. Therefore, the contact area between the positive electrode active material particles 11 and the solid electrolyte particles 31 increases, and lithium ion conductivity improves, so that the output of the battery increases. In addition, by including nickel as a constituent element of the positive electrode active material particles 11, the capacity density of the lithium ion secondary battery 1 is increased, and since the elution of metal in the charged state is small, the lithium ion secondary battery in the charged state 1 can improve the long-term reliability.

(被覆層12)
被覆層12は、正極活物質粒子11の表面の少なくとも一部を覆う。また、被覆層12は、ニッケルとは異なる元素Xを少なくとも含有する。被覆層12は、リチウムをさらに含有することが好ましい。
(Coating layer 12)
The coating layer 12 covers at least a part of the surface of the positive electrode active material particles 11. Further, the coating layer 12 contains at least an element X different from nickel. It is preferable that the coating layer 12 further contains lithium.

被覆層12は、非晶質である。さらに、元素Xと正極活物質粒子11内のリチウム以外の全金属元素とのモル比(原子数比)は、0.1〜10.0mol%である。このモル比は、元素Xのモル数(原子数)を正極活物質粒子11内のリチウム以外の全金属元素のモル数(原子数)で除算することで得られる。以下、このモル比を、単に「被覆層12の被覆量」とも称する。   The coating layer 12 is amorphous. Further, the molar ratio (atomic ratio) of the element X to all metal elements other than lithium in the positive electrode active material particles 11 is 0.1 to 10.0 mol%. This molar ratio is obtained by dividing the number of moles (number of atoms) of the element X by the number of moles (number of atoms) of all metal elements other than lithium in the positive electrode active material particles 11. Hereinafter, this molar ratio is also simply referred to as “the coating amount of the coating layer 12”.

ここで、元素Xは、ニッケルとは異なる元素であり、金属元素及び半金属元素のうち少なくとも1種であることが好ましい。元素Xは、Y,La,Ce,Nd,Sm,Eu,Ti,Zr,V,Nb,Cr,Mn,Fe,Co,Cu,Zn,Al,Si,Ga、Ge,及びInからなる群から選択される少なくとも1種であることがより好ましい。元素Xは、これらの元素のうち、Zr以外の元素であってもよい。被覆層12は、上記組成を有することで、正極活物質粒子11の表面に存在する遷移金属元素と固体電解質粒子31の表面に存在する硫黄元素との副反応を抑制することができ、ひいては、リチウムイオン二次電池1の出力を向上することができる。   Here, the element X is an element different from nickel, and is preferably at least one of a metal element and a metalloid element. Element X is selected from the group consisting of Y, La, Ce, Nd, Sm, Eu, Ti, Zr, V, Nb, Cr, Mn, Fe, Co, Cu, Zn, Al, Si, Ga, Ge, and In. More preferably, it is at least one selected. The element X may be an element other than Zr among these elements. The coating layer 12 having the above composition can suppress a side reaction between the transition metal element existing on the surface of the positive electrode active material particles 11 and the sulfur element existing on the surface of the solid electrolyte particles 31, and The output of the lithium ion secondary battery 1 can be improved.

(その他の添加剤)
正極層10には、被覆粒子10aに加えて、例えば、導電剤、結着剤、電解質、フィラー、分散剤、イオン導電剤等の添加剤が適宜選択され配合されていてもよい。
(Other additives)
In the positive electrode layer 10, in addition to the coated particles 10a, for example, additives such as a conductive agent, a binder, an electrolyte, a filler, a dispersant, and an ionic conductive agent may be appropriately selected and blended.

上記導電剤としては、例えば、黒鉛、カーボンブラック、アセチレンブラック、ケッチェンブラック、炭素繊維、金属粉等が挙げられ、上記結着剤としては、例えば、ポリテトラフルオロエチレン、ポリフッ化ビニリデン、ポリエチレン等が挙げられる。上記電解質としては、後述する硫化物系固体電解質等が挙げられる。また、上記フィラー、分散剤、イオン導電剤等としては、通常リチウムイオン二次電池の電極に用いられる公知の物質を用いることができる。   Examples of the conductive agent include graphite, carbon black, acetylene black, Ketjen black, carbon fiber, and metal powder. Examples of the binder include polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene. Is mentioned. Examples of the electrolyte include a sulfide-based solid electrolyte described below. In addition, as the filler, dispersant, ionic conductive agent, and the like, a known substance that is generally used for an electrode of a lithium ion secondary battery can be used.

(2.2.負極層20)
(負極活物質粒子21)
本実施形態に係る負極層20に含まれる負極活物質粒子21としては、リチウムとの合金化、又は、リチウムの可逆的な吸蔵及び放出が可能な物質であれば特に限定されず、例えば、リチウム、インジウム、スズ、アルミニウム、ケイ素等の金属及びこれらの合金や、Li4/3Ti5/3、SnO等の遷移金属酸化物や、人造黒鉛、黒鉛炭素繊維、樹脂焼成炭素、熱分解気相成長炭素、コークス、メソカーボンマイクロビーズ(MCMB)、フルフリルアルコール樹脂焼成炭素、ポリアセン、ピッチ系炭素繊維、気相成長炭素繊維、天然黒鉛及び難黒鉛化性炭素等の炭素材料などが挙げられる。これらの負極活物質粒子21は、単独で用いられてもよく、2種以上が併用されてもよい。
(2.2. Negative electrode layer 20)
(Negative electrode active material particles 21)
The negative electrode active material particles 21 included in the negative electrode layer 20 according to the present embodiment are not particularly limited as long as they can be alloyed with lithium or can reversibly occlude and release lithium. , Indium, tin, aluminum, silicon and other metals and alloys thereof, transition metal oxides such as Li 4/3 Ti 5/3 O 4 and SnO, artificial graphite, graphite carbon fiber, resin calcined carbon, pyrolysis Carbon materials such as vapor-grown carbon, coke, mesocarbon microbeads (MCMB), calcined furfuryl alcohol resin carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon. Can be These negative electrode active material particles 21 may be used alone or in combination of two or more.

(その他の添加剤)
なお、負極層20には、負極活物質粒子21の粒子に加えて、例えば、導電剤、結着剤、電解質、フィラー、分散剤、イオン導電剤等の添加剤が適宜選択され配合されていてもよい。これらの具体例としては、上述した正極層10と同様の物質が挙げられる。
(Other additives)
In addition, in the negative electrode layer 20, in addition to the particles of the negative electrode active material particles 21, for example, additives such as a conductive agent, a binder, an electrolyte, a filler, a dispersant, and an ionic conductive agent are appropriately selected and blended. Is also good. Specific examples thereof include the same substances as those of the positive electrode layer 10 described above.

(2.3.固体電解質層30)
本実施形態に係る固体電解質層30は、固体電解質粒子31を含む。固体電解質粒子31は、好ましくは硫化物系固体電解質粒子である。固体電解質粒子31は、ケイ素、リン、及びホウ素からなる群から選ばれる一種以上の元素を含有する硫化物系固体電解質粒子であることがより好ましい。これらの条件を満たす固体電解質粒子31、すなわち硫化物系固体電解質は、リチウムイオン伝導性が他の無機化合物より高いことが知られている。固体電解質粒子31の好ましい具体例は、LiS及びPである。他の例としては、SiS、GeS、B等が挙げられる。これらは混合して使用されてもよい。また、固体電解質粒子31には、適宜、LiPOやハロゲン、ハロゲン化合物等を添加されていてもよい。
(2.3. Solid electrolyte layer 30)
The solid electrolyte layer 30 according to the present embodiment includes solid electrolyte particles 31. The solid electrolyte particles 31 are preferably sulfide-based solid electrolyte particles. The solid electrolyte particles 31 are more preferably sulfide-based solid electrolyte particles containing one or more elements selected from the group consisting of silicon, phosphorus, and boron. It is known that the solid electrolyte particles 31 satisfying these conditions, that is, the sulfide-based solid electrolyte, have higher lithium ion conductivity than other inorganic compounds. Preferred specific examples of the solid electrolyte particles 31 are Li 2 S and P 2 S 5 . Other examples include SiS 2 , GeS 2 , B 2 S 3 and the like. These may be used as a mixture. Further, Li 3 PO 4 , halogen, a halogen compound, or the like may be appropriately added to the solid electrolyte particles 31.

(3.リチウムイオン二次電池の製造方法)
以上、本発明の好適な実施形態に係るリチウムイオン二次電池1の構成について詳細に説明したが、続いて、上述した構成を有するリチウムイオン二次電池1の製造方法について説明する。リチウムイオン二次電池1は、正極層10、負極層20及び固体電解質層30を作製した後に、これらの各層を積層することにより製造することができる。以下、各工程について詳述する。
(3. Method for producing lithium ion secondary battery)
The configuration of the lithium ion secondary battery 1 according to the preferred embodiment of the present invention has been described in detail above. Next, a method for manufacturing the lithium ion secondary battery 1 having the above configuration will be described. The lithium ion secondary battery 1 can be manufactured by forming the positive electrode layer 10, the negative electrode layer 20, and the solid electrolyte layer 30, and then stacking these layers. Hereinafter, each step will be described in detail.

(3−1.正極活物質粒子11の製造方法)
次に、正極活物質粒子11の製造方法について説明する。正極活物質粒子11の製造方法は、特に制限されないが、例えば、共沈法を用いることできる。以下では、かかる共沈法を用いた正極活物質粒子11の製造方法について一例を挙げて説明を行う。
(3-1. Method for producing positive electrode active material particles 11)
Next, a method for producing the positive electrode active material particles 11 will be described. The method for producing the positive electrode active material particles 11 is not particularly limited. For example, a coprecipitation method can be used. Hereinafter, a method for producing the positive electrode active material particles 11 using the coprecipitation method will be described with reference to an example.

まず、硫酸ニッケル6水和物(NiSO・6HO)、および金属元素Mを含む化合物をイオン交換水に溶解させて、混合水溶液を製造する。ここで、硫酸ニッケル6水和物、および金属元素Mを含む化合物の総質量は、混合水溶液の総質量に対して、例えば20質量%程度であればよい。また、硫酸ニッケル6水和物、および金属元素Mを含む化合物は、NiおよびMの各元素のモル(mole)比が所望の値となるように混合される。なお、各元素のモル比は、製造されるリチウムニッケル複合酸化物の組成に応じて決定されが、例えば、LiNi0.8Co0.15Al0.05を製造する場合、各元素のモル比Ni:Co:Alは80:15:5となる。 First, a mixed aqueous solution is produced by dissolving nickel sulfate hexahydrate (NiSO 4 .6H 2 O) and a compound containing the metal element M in ion-exchanged water. Here, the total mass of the compound containing nickel sulfate hexahydrate and the metal element M may be, for example, about 20% by mass with respect to the total mass of the mixed aqueous solution. The nickel sulfate hexahydrate and the compound containing the metal element M are mixed so that the mole ratio of each of the elements Ni and M becomes a desired value. The molar ratio of each element is determined according to the composition of the lithium nickel composite oxide to be produced. For example, when producing LiNi 0.8 Co 0.15 Al 0.05 O 2 , The molar ratio Ni: Co: Al is 80: 15: 5.

なお、金属元素Mは、化学式1で示される正極活物質を作製する場合、Co、Mn、AlおよびMgからなる群から選ばれる1種以上の元素であり、化学式2で示される正極活物質を作製する場合、CoおよびMnからなる群から選ばれる1種以上の元素である。   The metal element M is one or more elements selected from the group consisting of Co, Mn, Al, and Mg when the positive electrode active material represented by Chemical Formula 1 is prepared. When producing, it is one or more elements selected from the group consisting of Co and Mn.

また、反応層に所定量(例えば500ml)のイオン交換水を投入し、このイオン交換水の温度を50℃に維持する。以下、反応層内の水溶液を反応層水溶液と称する。次に、窒素等の不活性ガス(gas)によってイオン交換水をバブリング(bubbling)することによって溶存酸素を除去する。   Further, a predetermined amount (for example, 500 ml) of ion-exchanged water is charged into the reaction layer, and the temperature of the ion-exchanged water is maintained at 50 ° C. Hereinafter, the aqueous solution in the reaction layer is referred to as a reaction layer aqueous solution. Next, dissolved oxygen is removed by bubbling the ion-exchanged water with an inert gas (gas) such as nitrogen.

ついで、反応層内のイオン交換水を撹拌し、イオン交換水の温度を50℃に維持しながら、上述した混合水溶液をイオン交換水に滴下する。さらに、イオン交換水に、飽和NaOH水溶液を混合水溶液のNi、Co、Alに対して過剰量滴下する。なお、滴下中は、反応層水溶液のpHを11.5に、温度を50℃に維持する。混合水溶液及び飽和NaOH水溶液の滴下速度は特に制限されないが、早過ぎると均一な前駆体(共沈水酸化物塩)が得られない可能性がある。例えば、滴下速度は、3ml/min程度とすればよい。混合水溶液及び飽和NaOH水溶液の滴下は、所定時間、例えば10時間程度で行う。これにより、各金属元素の水酸化物塩が共沈する。   Next, while stirring the ion-exchanged water in the reaction layer and maintaining the temperature of the ion-exchanged water at 50 ° C., the above-mentioned mixed aqueous solution is dropped into the ion-exchanged water. Further, a saturated aqueous solution of NaOH is added dropwise to the ion-exchanged water in excess of Ni, Co, and Al in the mixed aqueous solution. During the dropping, the pH of the reaction layer aqueous solution was maintained at 11.5 and the temperature was maintained at 50 ° C. The dropping speed of the mixed aqueous solution and the saturated NaOH aqueous solution is not particularly limited, but if it is too fast, a uniform precursor (coprecipitated hydroxide salt) may not be obtained. For example, the dropping speed may be about 3 ml / min. The dropping of the mixed aqueous solution and the saturated NaOH aqueous solution is performed for a predetermined time, for example, about 10 hours. Thereby, the hydroxide salt of each metal element is co-precipitated.

続いて、固液分離(例えば吸引ろ過)を行い、共沈水酸化物塩を反応層水溶液から取り出し、取り出した共沈水酸化物塩をイオン交換水で洗浄する。さらに、共沈水酸化物塩を真空乾燥させる。この時の温度は、例えば、100℃程度とすればよく、乾燥時間は、例えば、10時間程度とすればよい。   Subsequently, solid-liquid separation (for example, suction filtration) is performed, the coprecipitated hydroxide salt is taken out from the aqueous solution of the reaction layer, and the taken out coprecipitated hydroxide salt is washed with ion-exchanged water. Further, the coprecipitated hydroxide salt is vacuum dried. The temperature at this time may be, for example, about 100 ° C., and the drying time may be, for example, about 10 hours.

次に、乾燥後の共沈水酸化物塩を乳鉢で数分間粉砕し、乾燥粉末を得る。そして、乾燥粉末と、水酸化リチウム(LiOH)とを混合することで、混合粉体を生成する。ここで、LiとNi+M(=Me)とのモル比は、リチウムニッケル複合酸化物の組成に応じて決定される。例えば、LiNi0.8Co0.15Al0.05を製造する場合、LiとMe(=Ni+Co+Al)とのモル比Li:Meは1.0:1.0となる。ここで、Meは、正極活物質中のリチウム以外の全金属元素を示す。 Next, the dried coprecipitated hydroxide salt is ground in a mortar for several minutes to obtain a dry powder. Then, a mixed powder is generated by mixing the dry powder and lithium hydroxide (LiOH). Here, the molar ratio between Li and Ni + M (= Me) is determined according to the composition of the lithium nickel composite oxide. For example, when manufacturing LiNi 0.8 Co 0.15 Al 0.05 O 2 , the molar ratio Li: Me of Li and Me (= Ni + Co + Al) is 1.0: 1.0. Here, Me indicates all metal elements other than lithium in the positive electrode active material.

さらに、この混合粉体を焼成する。なお、混合粉体中のニッケル原子は還元されやすいため、上記の焼成は、酸化性雰囲気下で行われることが好ましい。酸化性雰囲気下とは、例えば、酸素雰囲気下である。また、焼成時間、焼成温度は任意に調整されればよい。焼成温度は、例えば、700〜800℃程度とすればよく、焼成時間は、例えば、10時間程度とすればよい。以上の工程により、正極活物質粒子11を作製する。   Further, the mixed powder is fired. Note that, since the nickel atoms in the mixed powder are easily reduced, the above-described firing is preferably performed in an oxidizing atmosphere. The oxidizing atmosphere is, for example, an oxygen atmosphere. In addition, the firing time and the firing temperature may be arbitrarily adjusted. The firing temperature may be, for example, about 700 to 800 ° C., and the firing time may be, for example, about 10 hours. Through the above steps, the positive electrode active material particles 11 are produced.

上記の工程で得られた正極活物質粒子11は、粒度分布を有している。そこで、正極活物質粒子11の平均粒径が所望の値となるように、分級を行ってもよい。正極活物質粒子11は、例えば遠心力型分級装置(例えば、ホソカワミクロン社製ピコライン)によって、任意の平均粒径に分級することが可能である。正極活物質粒子11の平均粒径は、レーザ回折・散乱式粒子径分布測定装置(例えば、日機装株式会社製マイクロトラックMT−3000II)によって測定可能である。   The positive electrode active material particles 11 obtained in the above steps have a particle size distribution. Therefore, classification may be performed so that the average particle diameter of the positive electrode active material particles 11 becomes a desired value. The positive electrode active material particles 11 can be classified into an arbitrary average particle size by, for example, a centrifugal force classifier (for example, a picoline manufactured by Hosokawa Micron Corporation). The average particle size of the positive electrode active material particles 11 can be measured by a laser diffraction / scattering type particle size distribution measuring device (for example, Microtrack MT-3000II manufactured by Nikkiso Co., Ltd.).

(3.2.被覆粒子10aの製造方法)
次に、被覆粒子10aの製造方法について説明する。まず、リチウムアルコキシドと元素Xのアルコキシドとをアルコール、アセト酢酸エチル等の有機溶媒及び水からなる溶媒中で撹拌混合することで、リチウム及び元素Xのアルコール溶液(塗布液)を調製する。元素Xは、Y,La,Ce,Nd,Sm,Eu,Ti,Zr,V,Nb,Cr,Mn,Fe,Co,Cu,Zn,Al,Si,Ga、Ge,及びInからなる群から選択される少なくとも1種であることが好ましい。
(3.2. Method for producing coated particle 10a)
Next, a method for producing the coated particles 10a will be described. First, an alcohol solution (coating solution) of lithium and element X is prepared by stirring and mixing a lithium alkoxide and an alkoxide of element X in an organic solvent such as alcohol and ethyl acetoacetate and water. Element X is selected from the group consisting of Y, La, Ce, Nd, Sm, Eu, Ti, Zr, V, Nb, Cr, Mn, Fe, Co, Cu, Zn, Al, Si, Ga, Ge, and In. Preferably, at least one selected from them is used.

リチウムアルコキシド及び元素Xのアルコキシドは、リチウム及び元素Xを含む有機物(例えば有機リチウム等)とアルコールとを反応させることにより得ることができる。また、撹拌混合の時間は特に限定されないが、例えば、30分程度とすればよい。なお、アセト酢酸エチル等のCH−CO−CH−CO−O−Rの構造を有する化合物は、該構造中のカルボニル基2個がキレート剤的に働き、不安定な金属を安定化させる効果があることから、ここでは、元素Xのアルコキシドの安定化剤として働くものである。 The lithium alkoxide and the alkoxide of the element X can be obtained by reacting an organic substance (for example, organic lithium or the like) containing lithium and the element X with an alcohol. The time for stirring and mixing is not particularly limited, but may be, for example, about 30 minutes. In a compound having a structure of CH 3 —CO—CH 2 —CO—OR, such as ethyl acetoacetate, two carbonyl groups in the structure act as a chelating agent to stabilize an unstable metal. Since it has an effect, it functions as a stabilizer for the alkoxide of the element X here.

次に、塗布液を上述した正極活物質粒子11と混合する。ここで、被覆層12の被覆量をn、元素Xのアルコキシドに含まれる元素Xのモル数(原子数)をn、正極活物質粒子11内のリチウム以外の全金属元素のモル数(原子数)をnとした場合、nはn/n*100で表される。 Next, the coating liquid is mixed with the positive electrode active material particles 11 described above. Here, the coating amount of the coating layer 12 is n, the number of moles (atoms) of the element X contained in the alkoxide of the element X is n 1 , If the number) was n 2, n is represented by n 1 / n 2 * 100.

ついで、塗布液と正極活物質粒子11との混合溶液を撹拌しながら40℃程度に加熱することで、アルコール等の溶媒を全て蒸発させる。溶媒の蒸発は、混合溶液に超音波を照射しながら行う。これにより、正極活物質粒子11の表面に、被覆層12の前駆体を担持することができる。   Next, the mixed solution of the coating liquid and the positive electrode active material particles 11 is heated to about 40 ° C. while stirring, thereby evaporating all the solvent such as alcohol. The solvent is evaporated while irradiating the mixed solution with ultrasonic waves. Thereby, the precursor of the coating layer 12 can be supported on the surface of the positive electrode active material particles 11.

さらに、正極活物質粒子11の粒子表面に担持された被覆層12の前駆体を焼成する。このとき、焼成温度を400℃未満とする。焼成温度を400℃未満とすることで、被覆層12を非晶質とすることができる。また、焼成時間は特に限定されないが、例えば、1〜2時間程度とすればよい。また、焼成は酸素ガスを吹き込みながら行う。酸素ガスを吹き込むことにより、ニッケルを含む正極材料内のニッケルの還元を抑制し容量を維持することができる。上記の工程により、被覆層12を正極活物質粒子11の表面に被覆させることができる。すなわち、被覆粒子10aを作製することができる。   Further, the precursor of the coating layer 12 supported on the surface of the positive electrode active material particles 11 is fired. At this time, the firing temperature is set to less than 400 ° C. By setting the firing temperature to less than 400 ° C., the coating layer 12 can be made amorphous. The firing time is not particularly limited, but may be, for example, about 1 to 2 hours. The firing is performed while blowing oxygen gas. By blowing oxygen gas, reduction of nickel in the positive electrode material containing nickel can be suppressed and the capacity can be maintained. Through the above steps, the coating layer 12 can be coated on the surface of the positive electrode active material particles 11. That is, the coated particles 10a can be manufactured.

(3.2.固体電解質粒子31の作製)
固体電解質粒子31の作製方法は特に制限されず、従来の方法が任意に適用可能である。例えば、固体電解質粒子31は、溶融急冷法やメカニカルミリング法(MM法)によって作製可能である。以下、固体電解質粒子31の作製方法の一例として、LiS及びPを含む固体電解質粒子31の作製方法について説明する。
(3.2. Production of solid electrolyte particles 31)
The method for producing the solid electrolyte particles 31 is not particularly limited, and a conventional method can be arbitrarily applied. For example, the solid electrolyte particles 31 can be produced by a melt quenching method or a mechanical milling method (MM method). Hereinafter, as an example of a method for producing the solid electrolyte particles 31, a method for producing the solid electrolyte particles 31 containing Li 2 S and P 2 S 5 will be described.

溶融急冷法による場合には、LiSとPとを所定量混合しペレット状にしたものを、真空中で所定の反応温度で反応させた後、急冷することにより、硫化物系固体電解質を得ることができる。この際の反応温度は、好ましくは400℃〜1000℃、より好ましくは、800℃〜900℃である。また、反応時間は、好ましくは0.1時間〜12時間、より好ましくは、1〜12時間である。さらに、上記反応物の急冷温度は、通常10℃以下、好ましくは0℃以下であり、その冷却速度は、通常1〜10000K/sec程度、好ましくは1〜1000K/secである。 In the case of the melt quenching method, a mixture of Li 2 S and P 2 S 5 in a predetermined amount and formed into pellets is reacted at a predetermined reaction temperature in a vacuum, and then quenched to obtain a sulfide-based material. A solid electrolyte can be obtained. The reaction temperature at this time is preferably from 400C to 1000C, more preferably from 800C to 900C. Further, the reaction time is preferably 0.1 hour to 12 hours, more preferably 1 hour to 12 hours. Further, the quenching temperature of the reactant is usually 10 ° C. or lower, preferably 0 ° C. or lower, and the cooling rate is usually about 1 to 10,000 K / sec, preferably 1 to 1000 K / sec.

MM法による場合には、LiSとPとを所定量混合し、メカニカルミリング法にて所定時間反応させることで、硫化物系固体電解質を得ることができる。上記原料を用いたメカニカルミリング法は、室温で反応を行うことができるという利点がある。MM法によれば、室温で固体電解質を製造できるため、原料の熱分解が起こらず、仕込み組成の固体電解質を得ることができる。MM法の回転速度及び回転時間は特に限定されないが、回転速度が速いほど固体電解質の生成速度が速くなり、回転時間が長いほど固体電解質ヘの原料の転化率が高くなる。 In the case of using the MM method, a sulfide-based solid electrolyte can be obtained by mixing a predetermined amount of Li 2 S and P 2 S 5 and reacting them by a mechanical milling method for a predetermined time. The mechanical milling method using the above raw materials has an advantage that the reaction can be performed at room temperature. According to the MM method, since a solid electrolyte can be produced at room temperature, the raw material does not undergo thermal decomposition, and a solid electrolyte having a charged composition can be obtained. The rotation speed and rotation time of the MM method are not particularly limited, but the higher the rotation speed, the higher the solid electrolyte generation speed, and the longer the rotation time, the higher the conversion of the raw material to the solid electrolyte.

その後、得られた固体電解質を所定の温度で熱処理した後に、粉砕して固体電解質粒子31とする。LiSとPを含む硫化物との混合比は、モル比で、通常50:50〜80:20、好ましくは60:40〜75:25である。 Thereafter, the obtained solid electrolyte is heat-treated at a predetermined temperature, and then pulverized to obtain solid electrolyte particles 31. The mixing ratio of Li 2 S to the sulfide containing P 2 S 5 is usually 50:50 to 80:20, preferably 60:40 to 75:25, in molar ratio.

(3.3.正極層10の作製)
被覆粒子10a、固体電解質粒子31、及び各種添加剤との混合物を溶媒に添加することで、スラリー又はペースト状の正極合剤を作製する。ここで、溶媒は、正極合剤の作製に使用可能なものであれば特に制限されないが、非極性溶媒が特に好ましい。非極性溶媒は固体電解質粒子31と反応しにくいからである。ついで、得られた正極合剤をドクターブレード等を用いて集電体に塗布し、乾燥する。ついで、集電体及び正極合剤層を圧延ロール等で圧密化することで、正極層10を得る。
(3.3. Production of positive electrode layer 10)
A slurry or paste-like positive electrode mixture is produced by adding a mixture of the coating particles 10a, the solid electrolyte particles 31, and various additives to a solvent. Here, the solvent is not particularly limited as long as it can be used for producing the positive electrode mixture, but a non-polar solvent is particularly preferable. This is because the non-polar solvent hardly reacts with the solid electrolyte particles 31. Next, the obtained positive electrode mixture is applied to a current collector using a doctor blade or the like, and dried. Next, the positive electrode layer 10 is obtained by consolidating the current collector and the positive electrode mixture layer with a rolling roll or the like.

このとき用いることができる集電体としては、例えば、ステンレス鋼、チタン、アルミニウム、又は、これらの合金等からなる板状体や箔状体等が挙げられる。なお、集電体を用いずに、正極合剤をペレット状に圧密化成形して正極層10としてもよい。   The current collector that can be used at this time includes, for example, a plate-like body or a foil-like body made of stainless steel, titanium, aluminum, or an alloy thereof. The positive electrode layer 10 may be formed by compacting the positive electrode mixture into pellets without using the current collector.

(3.4.負極層20の作製)
負極層20の作製方法は以下の通りである。例えば、上記負極活物質粒子21、固体電解質粒子31及び各種添加剤との混合物を溶媒に添加することで、スラリー又はペースト状の負極合剤を作製する。ここで、溶媒は、負極合剤の作製に使用可能なものであれば特に制限されないが、非極性溶媒が特に好ましい。非極性溶媒は固体電解質粒子31と反応しにくいからである。ついで、得られた負極合剤をドクターブレード等を用いて集電体に塗布し、乾燥する。ついで、集電体及び負極合剤層を圧延ロール等で圧密化することで、負極層20を得る。
(3.4. Production of Negative Electrode Layer 20)
The method for producing the negative electrode layer 20 is as follows. For example, a slurry or paste-like negative electrode mixture is prepared by adding a mixture of the negative electrode active material particles 21, the solid electrolyte particles 31, and various additives to a solvent. Here, the solvent is not particularly limited as long as it can be used for producing the negative electrode mixture, but a non-polar solvent is particularly preferable. This is because the non-polar solvent hardly reacts with the solid electrolyte particles 31. Next, the obtained negative electrode mixture is applied to a current collector using a doctor blade or the like, and dried. Next, the negative electrode layer 20 is obtained by consolidating the current collector and the negative electrode mixture layer with a rolling roll or the like.

このとき用いることができる集電体としては、例えば、銅、ステンレス鋼、ニッケル又は、これらの合金等からなる板状体や箔状体等が挙げられる。なお、集電体を用いずに、上記負極活物質粒子21と各種添加剤との混合物をペレット状に圧密化成形して負極層20としてもよい。また、負極活物質粒子21として金属又はその合金を使用する場合、金属シート(箔)をそのまま使用してもよい。   Examples of the current collector that can be used at this time include a plate-like body and a foil-like body made of copper, stainless steel, nickel, or an alloy thereof. The negative electrode layer 20 may be formed by compacting and molding a mixture of the negative electrode active material particles 21 and various additives into pellets without using a current collector. When a metal or an alloy thereof is used as the negative electrode active material particles 21, a metal sheet (foil) may be used as it is.

(3.5.固体電解質層30の作製)
固体電解質層30の作製方法は以下の通りである。固体電解質粒子31を、例えば、ブラスト法、エアロゾルデポジション法、コールドスプレー法、スパッタリング法、気相成長法(CVD)、溶射法等の公知の製膜方法を用いて製膜することにより、固体電解質層30を作製できる。また、固体電解質粒子31と溶媒やバインダー(結着材や高分子化合物等)を混合した溶液を塗布した後、溶媒を除去し製膜化する方法を用いてもよい。また、固体電解質粒子31自体や固体電解質粒子31とバインダー(結着材や高分子化合物等)や支持体(固体電解質層30の強度を補強させたり、固体電解質粒子31自体の短絡を防ぐための材料や化合物等)を混合した電解質をプレスすることで製膜することもできる。
(3.5. Production of solid electrolyte layer 30)
The method for producing the solid electrolyte layer 30 is as follows. The solid electrolyte particles 31 are formed by a known film forming method such as a blast method, an aerosol deposition method, a cold spray method, a sputtering method, a vapor deposition method (CVD), and a thermal spraying method. The electrolyte layer 30 can be manufactured. Alternatively, a method in which a solution in which the solid electrolyte particles 31 are mixed with a solvent or a binder (such as a binder or a high molecular compound) is applied, and then the solvent is removed to form a film may be used. In addition, the solid electrolyte particles 31 and the solid electrolyte particles 31 and a binder (binder or polymer compound) or a support (for reinforcing the strength of the solid electrolyte layer 30 or preventing a short circuit of the solid electrolyte particles 31 themselves) A film can also be formed by pressing an electrolyte mixed with materials and compounds.

(3.6.各層の積層)
以上のようにして得られた正極層10、固体電解質層30及び負極層20をこの順で積層し、プレス等することにより、本実施形態に係るリチウムイオン二次電池1を製造することができる。
(3.6. Lamination of each layer)
The positive electrode layer 10, the solid electrolyte layer 30, and the negative electrode layer 20 obtained as described above are stacked in this order and pressed to manufacture the lithium ion secondary battery 1 according to the present embodiment. .

次に、本実施形態の実施例について説明する。もちろん、本発明は、以下の実施例のみに限定されるわけではない。   Next, an example of the present embodiment will be described. Of course, the present invention is not limited only to the following examples.

(1.実施例1)
(1.1正極活物質粒子11の作製)
実施例1では、以下の工程により被覆粒子10aを作製した。硫酸ニッケル6水和物(NiSO・6HO)、硫酸コバルト5水和物(CoSO・5HO)、および硝酸アルミニウム(Al(NO)をイオン交換水に溶解させ、混合水溶液を製造した。ここで、硫酸ニッケル6水和物、硫酸コバルト5水和物、および硝酸アルミニウムの総質量は、混合水溶液の総質量に対して、20質量%とした。また、硫酸ニッケル6水和物、硫酸コバルト5水和物、および硝酸アルミニウムの混合比は、Ni、Co、およびAlの各元素のモル比が、Ni:Co:Al=80:15:5となるように設定した。
(1. Example 1)
(1.1 Preparation of Positive Electrode Active Material Particles 11)
In Example 1, the coated particles 10a were produced by the following steps. Nickel sulfate hexahydrate (NiSO 4 · 6H 2 O) , dissolved cobalt pentahydrate sulfate (CoSO 4 · 5H 2 O) , and aluminum nitrate (Al (NO 3) 3) in deionized water, mixed An aqueous solution was prepared. Here, the total mass of nickel sulfate hexahydrate, cobalt sulfate pentahydrate, and aluminum nitrate was 20% by mass with respect to the total mass of the mixed aqueous solution. The mixing ratio of nickel sulfate hexahydrate, cobalt sulfate pentahydrate, and aluminum nitrate is such that the molar ratio of each element of Ni, Co, and Al is Ni: Co: Al = 80: 15: 5. It was set to become.

また、反応層に所定量(例えば500ml)のイオン交換水を投入し、このイオン交換水の温度を50℃に維持した。次に、窒素ガスによってイオン交換水をバブリングすることによって溶存酸素を除去した。   Further, a predetermined amount (for example, 500 ml) of ion-exchanged water was charged into the reaction layer, and the temperature of the ion-exchanged water was maintained at 50 ° C. Next, dissolved oxygen was removed by bubbling ion-exchanged water with nitrogen gas.

ついで、反応層内のイオン交換水を撹拌し、イオン交換水の温度を50℃に維持しながら、上述した混合水溶液をイオン交換水に滴下した。さらに、イオン交換水に、飽和NaOH水溶液を混合水溶液のNi、Co、Alに対して過剰量滴下した。滴下中は、反応層水溶液のpHを11.5に、温度を50℃に維持した。混合水溶液及び飽和NaOH水溶液の滴下速度は3ml/min程度とした。また、撹拌速度は周速で4〜5m/sとした。混合水溶液及び飽和NaOH水溶液の滴下は、10時間程度で行った。これにより、各金属元素の水酸化物塩が共沈した。   Next, the mixed aqueous solution was dropped into the ion-exchanged water while stirring the ion-exchanged water in the reaction layer and maintaining the temperature of the ion-exchanged water at 50 ° C. Further, a saturated aqueous NaOH solution was added dropwise to the ion-exchanged water in excess of Ni, Co, and Al in the mixed aqueous solution. During the dropwise addition, the pH of the reaction layer aqueous solution was maintained at 11.5, and the temperature was maintained at 50 ° C. The drop rate of the mixed aqueous solution and the saturated NaOH aqueous solution was about 3 ml / min. The stirring speed was 4 to 5 m / s in peripheral speed. The dropping of the mixed aqueous solution and the saturated aqueous solution of NaOH was performed in about 10 hours. Thereby, the hydroxide salt of each metal element co-precipitated.

続いて、吸引ろ過を行い、共沈水酸化物塩を反応層水溶液から取り出し、取り出した共沈水酸化物塩をイオン交換水で洗浄した。さらに、共沈水酸化物塩を真空乾燥させた。この時の温度は、100℃とし、乾燥時間は、10時間とした。   Subsequently, suction filtration was performed to remove the coprecipitated hydroxide salt from the aqueous solution of the reaction layer, and the coprecipitated hydroxide salt was washed with ion-exchanged water. Further, the coprecipitated hydroxide salt was dried under vacuum. The temperature at this time was 100 ° C., and the drying time was 10 hours.

次に、乾燥後の共沈水酸化物塩を乳鉢で数分間粉砕し、乾燥粉末を得た。そして、乾燥粉末と、水酸化リチウム(LiOH)とを混合することで、混合粉体を生成した。ここで、LiとNi+Mn+Al(=Me)とのモル比Li:Meは1.0:1.0とした。   Next, the dried coprecipitated hydroxide salt was ground in a mortar for several minutes to obtain a dry powder. Then, a mixed powder was produced by mixing the dry powder and lithium hydroxide (LiOH). Here, the molar ratio Li: Me of Li and Ni + Mn + Al (= Me) was set to 1.0: 1.0.

さらに、この混合粉体を酸化雰囲気下で焼成した。焼成温度は、700〜800℃とし、焼成時間は、10時間とした。以上の工程により、実施例1に係る正極活物質粒子11(以下、「正極活物質粒子11−1」とも称する)を作製した。正極活物質粒子11−1の組成は、LiNi0.8Co0.15Al0.05で示される。 Further, the mixed powder was fired in an oxidizing atmosphere. The firing temperature was 700 to 800 ° C., and the firing time was 10 hours. Through the above steps, the positive electrode active material particles 11 according to Example 1 (hereinafter, also referred to as “positive electrode active material particles 11-1”) were produced. The composition of the positive electrode active material particles 11-1 is represented by LiNi 0.8 Co 0.15 Al 0.05 O 2 .

ついで、正極活物質粒子11−1の平均粒径(D50)をレーザ回折・散乱式粒度分布計(日機装株式会社製マイクロトラックMT−3000II)で測定したところ、7.0μmであった。   Then, the average particle diameter (D50) of the positive electrode active material particles 11-1 was measured by a laser diffraction / scattering particle size distribution analyzer (Microtrack MT-3000II manufactured by Nikkiso Co., Ltd.), and it was 7.0 μm.

(1.2.被覆粒子10aの作製)
実施例1では、以下の工程により被覆粒子10aを作製した。リチウムメトキシドメタノール10%溶液0.2質量gと、ランタン(III)プロポキシドとを、テトラヒドロフランとアセト酢酸エチルとの混合溶液中で30分混合した。この混合溶液中に、正極活物質粒子11−1を添加した。ここで、ランタン(III)プロポキシドに含まれるランタンのモル数n、及び正極活物質粒子11−1内のリチウム以外の全金属元素のモル数nは、被覆層12の被覆量が1.0mol%となるように(すなわち、nとnとの比が1.0mol%となるように)調製した。
(1.2. Production of coated particles 10a)
In Example 1, the coated particles 10a were produced by the following steps. 0.2 mass g of a 10% lithium methoxide methanol solution and lanthanum (III) propoxide were mixed for 30 minutes in a mixed solution of tetrahydrofuran and ethyl acetoacetate. The positive electrode active material particles 11-1 were added to the mixed solution. Here, the number of moles n 1 of lanthanum contained in lanthanum (III) propoxide and the number of moles n 2 of all metal elements other than lithium in the positive electrode active material particles 11-1 are such that the coating amount of the coating layer 12 is as a .0mol% (i.e., such that the ratio of n 1 and n 2 is 1.0 mol%) was prepared.

ついで、得られた混合溶液を40℃に加熱して撹拌しながら溶媒を全て蒸発させた。溶媒の蒸発は、混合溶液には超音波を照射しながら行った。これにより正極活物質粒子11−1の表面にリチウム−ランタン酸化物の反応前駆体が担持された。さらに、正極活物質粒子11−1表面へ担持されたリチウム−ランタン酸化物の前駆体を、酸素を吹き込みながら350℃で1時間焼成した。これにより、実施例1に係る被覆粒子10a(以下、「被覆粒子10a−1」とも称する)を得た。実施例1の被覆層12は、リチウム−ランタン酸化物で構成され、かつ被覆量は1.0mol%となる。また、被覆粒子10aの粉末X線回折測定を行ったところ、正極活物質に由来するピークだけが確認された。この結果、被覆層12が非晶質であることが確認された。   Then, the obtained mixed solution was heated to 40 ° C., and the solvent was completely evaporated while stirring. The solvent was evaporated while irradiating the mixed solution with ultrasonic waves. As a result, the reaction precursor of lithium-lanthanum oxide was supported on the surface of the positive electrode active material particles 11-1. Further, the precursor of the lithium-lanthanum oxide supported on the surface of the positive electrode active material particles 11-1 was fired at 350 ° C. for 1 hour while blowing oxygen. Thus, coated particles 10a according to Example 1 (hereinafter, also referred to as “coated particles 10a-1”) were obtained. The coating layer 12 of Example 1 is composed of lithium-lanthanum oxide, and has a coating amount of 1.0 mol%. In addition, when powder X-ray diffraction measurement of the coated particles 10a was performed, only peaks derived from the positive electrode active material were confirmed. As a result, it was confirmed that the coating layer 12 was amorphous.

(1.3.固体電解質粒子31の作製)
LiSとPとを80/20のモル比でメカニカルミリング処理(MM処理)により混合させることで、固体電解質粒子31を得た。固体電解質粒子31の平均粒径(D50)は、10μmであった。ここで、平均粒径は、固体電解質粒子31の二次粒子の平均粒径である。また、平均粒径の測定に際し、二次粒子は球体とみなした。測定は日機装株式会社製マイクロトラックMT−3000IIを用いて行った。
(1.3. Production of solid electrolyte particles 31)
Solid electrolyte particles 31 were obtained by mixing Li 2 S and P 2 S 5 at a molar ratio of 80/20 by mechanical milling (MM processing). The average particle size (D50) of the solid electrolyte particles 31 was 10 μm. Here, the average particle size is the average particle size of the secondary particles of the solid electrolyte particles 31. In measuring the average particle size, the secondary particles were regarded as spheres. The measurement was performed using Nikkiso Co., Ltd. Microtrack MT-3000II.

(1.4.リチウムイオン二次電池の作製)
以下の工程により、リチウムイオン二次電池1を作製した。なお、以下の工程は全て不活性ガス雰囲気下で行われた。被覆粒子10a−1と、固体電解質粒子31と、導電助剤としてのカーボンブラック粉末とを、60/35/5の質量比で乳鉢を用いて均質になるまで混合した。これにより、正極合剤を得た。この正極合剤30mgを、成形冶具中に挿入して、2ton/cmでプレス成形することで、正極合剤をペレット化した。そして、ペレット化された正極合剤を、ステンレス製集電体上に積層させることで、正極層10を作製した。
(1.4. Production of lithium ion secondary battery)
The lithium ion secondary battery 1 was manufactured by the following steps. The following steps were all performed in an inert gas atmosphere. The coated particles 10a-1, the solid electrolyte particles 31, and the carbon black powder as the conductive additive were mixed at a mass ratio of 60/35/5 using a mortar until they were homogeneous. Thus, a positive electrode mixture was obtained. 30 mg of this positive electrode mixture was inserted into a molding jig and press-molded at 2 ton / cm 2 to pelletize the positive electrode mixture. And the positive electrode layer 10 was produced by laminating the pelletized positive electrode mixture on a stainless steel current collector.

ついで、100mgの固体電解質粒子31を、成形冶具中に挿入して、2ton/cmでプレス成形することで、固体電解質層30を作製した。この成形冶具中に上記正極層を挿入し2ton/cmでプレス成形することで、固体電解質層30と正極層10とを一体化させた。 Next, 100 mg of the solid electrolyte particles 31 were inserted into a molding jig and press-molded at 2 ton / cm 2 to produce a solid electrolyte layer 30. The solid electrolyte layer 30 and the positive electrode layer 10 were integrated by inserting the positive electrode layer into this forming jig and press-forming at 2 ton / cm 2 .

ついで、固体電解質層30が正極層10と負極層20とで挟持されるように、成形冶具中に負極合剤として、黒鉛粉末(80℃で24時間真空乾燥したもの)30.0mgを挿入し、4ton/cmでプレス成形した。これにより、固体電解質層30と負極層20とを一体化させた。以上の工程により、試験用セルを得た。 Next, 30.0 mg of graphite powder (which was vacuum-dried at 80 ° C. for 24 hours) was inserted as a negative electrode mixture into a molding jig so that the solid electrolyte layer 30 was sandwiched between the positive electrode layer 10 and the negative electrode layer 20. And press-formed at 4 ton / cm 2 . Thereby, the solid electrolyte layer 30 and the negative electrode layer 20 were integrated. Through the above steps, a test cell was obtained.

(1.5.サイクル寿命試験)
得られた試験用セルを、25℃で、0.05Cの定電流で、上限電圧4.2Vまで充電し、放電終止電圧2.5Vまで0.05C放電する充放電サイクルを50サイクル繰り返した。そして、1サイクル目の放電容量に対する50サイクル目の放電容量の比を放電容量の維持率とした。放電容量の維持率はサイクル特性を示すパラメータであり、この値が大きいほどサイクル特性に優れている。
(1.5. Cycle life test)
The obtained test cell was charged at 25 ° C. with a constant current of 0.05 C up to an upper limit voltage of 4.2 V, and a charge / discharge cycle of discharging 0.05 C to a discharge end voltage of 2.5 V was repeated 50 times. Then, the ratio of the discharge capacity at the 50th cycle to the discharge capacity at the 1st cycle was defined as the maintenance rate of the discharge capacity. The maintenance ratio of the discharge capacity is a parameter indicating the cycle characteristics, and the larger the value is, the more excellent the cycle characteristics are.

(2.実施例2)
被覆層12の被覆量を0.1mol%とした他は、実施例1と同様の処理を行った。
(2. Example 2)
The same processing as in Example 1 was performed except that the coating amount of the coating layer 12 was 0.1 mol%.

(3.実施例3)
被覆層12の被覆量を10.0mol%とした他は、実施例1と同様の処理を行った。
(3. Example 3)
The same processing as in Example 1 was performed except that the coating amount of the coating layer 12 was 10.0 mol%.

(4.実施例4)
正極活物質粒子11−1を分級することで、平均粒径が3.0μmである正極活物質粒子11を作製した。それ以外は実施例1と同様の処理を行った。
(4. Example 4)
By classifying the positive electrode active material particles 11-1, the positive electrode active material particles 11 having an average particle size of 3.0 μm were produced. Otherwise, the same processing as in Example 1 was performed.

(5.実施例5)
正極活物質粒子11−1を分級することで、平均粒径が10.0μmである正極活物質粒子11を作製した。それ以外は実施例1と同様の処理を行った。
(5. Example 5)
By classifying the positive electrode active material particles 11-1, the positive electrode active material particles 11 having an average particle size of 10.0 μm were produced. Otherwise, the same processing as in Example 1 was performed.

(6.実施例6)
リチウムメトキシドメタノール10%溶液0.2質量gと、イットリウム(III)プロポキシドとを、イソプロパノールの溶液中で30分混合したことを除き、実施例1と同様の工程で被覆粒子10aを作製した。それ以外は実施例1と同様の処理を行った。
(6. Example 6)
Except that 0.2 mass g of a 10% solution of lithium methoxide methanol and yttrium (III) propoxide were mixed for 30 minutes in a solution of isopropanol, coated particles 10a were produced in the same steps as in Example 1. . Otherwise, the same processing as in Example 1 was performed.

(7.実施例7)
ランタンプロポキシドの代わりにセリウム(IV)プロポキシドを使用したことを除き、実施例1と同様の工程で被覆粒子10aを作製した。それ以外は実施例1と同様とした。
(7. Example 7)
Except that cerium (IV) propoxide was used instead of lanthanum propoxide, coated particles 10a were produced in the same steps as in Example 1. The other conditions were the same as in Example 1.

(8.実施例8)
リチウムメトキシドメタノール10%溶液0.2質量gと、アルミニウム(III)プロポキシドとを、イソプロパノールの溶液中で30分混合したことを除き、実施例1と同様の工程で被覆粒子10aを作製した。それ以外は実施例1と同様とした。
(8. Example 8)
Except that 0.2 mass g of a 10% solution of lithium methoxide methanol and aluminum (III) propoxide were mixed in a solution of isopropanol for 30 minutes, coated particles 10a were produced in the same process as in Example 1. . The other conditions were the same as in Example 1.

(9.実施例9)
リチウムメトキシドメタノール10%溶液0.2質量gと、ガリウム(III)プロポキシドとを、イソプロパノールの溶液中で30分混合したことを除き、実施例1と同様の工程で被覆粒子10aを作製した。それ以外は実施例1と同様とした。
(9. Example 9)
Except that 0.2 mass g of a 10% solution of lithium methoxide methanol and gallium (III) propoxide were mixed in an isopropanol solution for 30 minutes, coated particles 10a were produced in the same steps as in Example 1. . The other conditions were the same as in Example 1.

(10.実施例10)
リチウムメトキシドメタノール10%溶液0.2質量gと、インジウム(III)プロポキシドとを、イソプロパノールの溶液中で30分混合したことを除き、実施例1と同様の工程で被覆粒子10aを作製した。それ以外は実施例1と同様とした。
(10. Example 10)
Except that 0.2 mass g of a 10% solution of lithium methoxide methanol and indium (III) propoxide were mixed in a solution of isopropanol for 30 minutes, coated particles 10a were produced in the same steps as in Example 1. . The other conditions were the same as in Example 1.

(11.実施例11)
リチウムメトキシドメタノール10%溶液0.2質量gと、チタン(IV)プロポキシドとを、イソプロパノールの溶液中で30分混合したことを除き、実施例1と同様の工程で被覆粒子10aを作製した。それ以外は実施例1と同様とした。
(11. Example 11)
Except that 0.2 mass g of a 10% solution of lithium methoxide methanol and titanium (IV) propoxide were mixed in an isopropanol solution for 30 minutes, coated particles 10a were produced in the same process as in Example 1. . The other conditions were the same as in Example 1.

(12.実施例12)
リチウムメトキシドメタノール10%溶液0.2質量gと、ジルコニウム(IV)プロポキシドとを、イソプロパノールの溶液中で30分混合したことを除き、実施例1と同様の工程で正極活物質粒子11を作製した。それ以外は実施例1と同様とした。
(12. Example 12)
Except that 0.2 mass g of a 10% solution of lithium methoxide methanol and zirconium (IV) propoxide were mixed in a solution of isopropanol for 30 minutes, the positive electrode active material particles 11 were formed in the same process as in Example 1. Produced. The other conditions were the same as in Example 1.

(13.実施例13)
リチウムメトキシドメタノール10%溶液0.2質量gと、ニオブ(V)プロポキシドとを、イソプロパノールの溶液中で30分混合したことを除き、実施例1と同様の工程で正極活物質粒子11を作製した。それ以外は実施例1と同様とした。
(13. Example 13)
Except that 0.2 mass g of a 10% solution of lithium methoxide methanol and niobium (V) propoxide were mixed in a solution of isopropanol for 30 minutes, the positive electrode active material particles 11 were formed in the same process as in Example 1. Produced. The other conditions were the same as in Example 1.

(14.実施例14)
硝酸アルミニウムを硫酸マンガン7水和物に変更し、かつ、硫酸ニッケル6水和物、硫酸コバルト5水和物、および硫酸マンガン7水和物の混合比を、Ni、Co、およびMnの各元素のモル比が、Ni:Co:Mn=80:10:10となるように設定した他は、実施例1と同様の処理を行うことで、正極活物質粒子11を作製した。また、正極活物質粒子11を分級することで、平均粒径を9.0μmとした。それ以外は実施例1と同様の処理を行った。
(14. Example 14)
Aluminum nitrate was changed to manganese sulfate heptahydrate, and the mixing ratio of nickel sulfate hexahydrate, cobalt sulfate pentahydrate, and manganese sulfate heptahydrate was changed to Ni, Co, and Mn. The positive electrode active material particles 11 were produced by performing the same processing as in Example 1 except that the molar ratio was set to be Ni: Co: Mn = 80: 10: 10. The average particle diameter was adjusted to 9.0 μm by classifying the positive electrode active material particles 11. Otherwise, the same processing as in Example 1 was performed.

(15.実施例15)
硝酸アルミニウムを硫酸マンガン7水和物に変更し、かつ、硫酸ニッケル6水和物、硫酸コバルト5水和物、および硫酸マンガン7水和物の混合比を、Ni、Co、およびMnの各元素のモル比が、Ni:Co:Mn=50:20:30となるように設定した他は、実施例1と同様の処理を行うことで、正極活物質粒子11を作製した。また、正極活物質粒子11を分級することで、平均粒径を8.0μmとした。それ以外は実施例1と同様の処理を行った。
(15. Example 15)
Aluminum nitrate was changed to manganese sulfate heptahydrate, and the mixing ratio of nickel sulfate hexahydrate, cobalt sulfate pentahydrate, and manganese sulfate heptahydrate was changed to Ni, Co, and Mn. The positive electrode active material particles 11 were produced by performing the same processing as in Example 1 except that the molar ratio was set to be Ni: Co: Mn = 50: 20: 30. Moreover, the average particle diameter was adjusted to 8.0 μm by classifying the positive electrode active material particles 11. Otherwise, the same processing as in Example 1 was performed.

(16.実施例16)
硝酸アルミニウムを硫酸マンガン7水和物に変更し、かつ、硫酸ニッケル6水和物、硫酸コバルト5水和物、および硫酸マンガン7水和物の混合比を、Ni、Co、およびMnの各元素のモル比が、Ni:Co:Mn=1/3:1/3:1/3となるように設定した他は、実施例1と同様の処理を行うことで、正極活物質粒子11を作製した。また、正極活物質粒子11を分級することで、平均粒径を9.0μmとした。それ以外は実施例1と同様の処理を行った。
(16. Example 16)
Aluminum nitrate was changed to manganese sulfate heptahydrate, and the mixing ratio of nickel sulfate hexahydrate, cobalt sulfate pentahydrate, and manganese sulfate heptahydrate was changed to Ni, Co, and Mn. The positive electrode active material particles 11 were prepared by performing the same processing as in Example 1 except that the molar ratio of Ni: Co: Mn = 1/3: 1/3: 1/3 was set. did. The average particle diameter was adjusted to 9.0 μm by classifying the positive electrode active material particles 11. Otherwise, the same processing as in Example 1 was performed.

(17.実施例17)
硫酸ニッケル6水和物、硫酸コバルト5水和物、および硝酸アルミニウムの代わりに硫酸ニッケル6水和物及び硫酸マンガン7水和物を用い、かつ、これらの混合比を、Ni、およびMnの各元素のモル比が、Ni:Mn=5:15となるように設定した他は、実施例1と同様の処理を行うことで、正極活物質粒子11を作製した。また、正極活物質粒子11を分級することで、平均粒径を4.0μmとした。また、充電時の上限電圧を4.95Vとした。それ以外は実施例1と同様の処理を行った。
(17. Example 17)
Nickel sulfate hexahydrate and manganese sulfate heptahydrate were used in place of nickel sulfate hexahydrate, cobalt sulfate pentahydrate, and aluminum nitrate, and the mixing ratio of each of these components was Ni and Mn. Positive electrode active material particles 11 were produced by performing the same processing as in Example 1 except that the molar ratio of the elements was set to be Ni: Mn = 5: 15. The average particle diameter was set to 4.0 μm by classifying the positive electrode active material particles 11. The upper limit voltage during charging was 4.95V. Otherwise, the same processing as in Example 1 was performed.

(18.実施例18)
リチウムメトキシドメタノール溶液を使用しなかったこと以外は、実施例1と同様の処理を行うことで、被覆粒子10aを作製した。したがって、この被覆粒子10aには、リチウムが含まれていない。
(18. Example 18)
Except that the lithium methoxide methanol solution was not used, the same process as in Example 1 was performed to produce coated particles 10a. Therefore, the coated particles 10a do not contain lithium.

(19.比較例1)
正極活物質粒子11−1を被覆層12で被覆しなかったことを除き、実施例1と同様の処理を行った。
(19. Comparative Example 1)
The same process as in Example 1 was performed except that the positive electrode active material particles 11-1 were not covered with the coating layer 12.

(20.比較例2)
正極活物質粒子11−1を分級することで、平均粒径が1.0μmである正極活物質粒子11を作製した。それ以外は実施例1と同様の処理を行った。
(20. Comparative Example 2)
By classifying the cathode active material particles 11-1, the cathode active material particles 11 having an average particle size of 1.0 μm were produced. Otherwise, the same processing as in Example 1 was performed.

(21.比較例3)
正極活物質粒子11−1を分級することで、平均粒径が15.0μmである正極活物質粒子11を作製した。それ以外は実施例1と同様の処理を行った。
(21. Comparative Example 3)
By classifying the positive electrode active material particles 11-1, positive electrode active material particles 11 having an average particle size of 15.0 μm were produced. Otherwise, the same processing as in Example 1 was performed.

(22.比較例4)
被覆層12の被覆量を0.05mol%とした他は、実施例1と同様の処理を行った。
(22. Comparative Example 4)
The same processing as in Example 1 was performed except that the coating amount of the coating layer 12 was 0.05 mol%.

(23.比較例5)
被覆層12の被覆量を15.0mol%とした他は、実施例1と同様の処理を行った。
(23. Comparative Example 5)
The same processing as in Example 1 was performed except that the coating amount of the coating layer 12 was 15.0 mol%.

(24.比較例6)
被覆層12の前駆体の焼成温度を550℃とした他は、実施例1と同様の処理を行った。被覆粒子10aの粉末X線回折測定を行ったところ、酸化ランタンに由来するピークが確認された。この結果、被覆層12が結晶であることが確認された。
(24. Comparative Example 6)
The same processing as in Example 1 was performed except that the firing temperature of the precursor of the coating layer 12 was set to 550 ° C. When the powder X-ray diffraction measurement of the coated particles 10a was performed, a peak derived from lanthanum oxide was confirmed. As a result, it was confirmed that the coating layer 12 was crystalline.

実施例1〜18及び比較例1〜6に係る試験用セルの構成を表1に、評価を表2にそれぞれまとめて示す。   Table 1 shows the configurations of the test cells according to Examples 1 to 18 and Comparative Examples 1 to 6, and Table 2 shows the evaluations.

Figure 0006667985
Figure 0006667985

Figure 0006667985
Figure 0006667985

表1、2によれば、本実施形態の被覆粒子10aを有する実施例1〜18は、被覆粒子10aを有しない比較例1〜6よりも放電容量及びサイクル特性が顕著に向上していることが確認された。   According to Tables 1 and 2, Examples 1 to 18 having the coated particles 10a of the present embodiment have significantly improved discharge capacity and cycle characteristics as compared with Comparative Examples 1 to 6 having no coated particles 10a. Was confirmed.

以上、添付図面を参照しながら本発明の好適な実施形態について詳細に説明したが、本発明はかかる例に限定されない。本発明の属する技術の分野における通常の知識を有する者であれば、特許請求の範囲に記載された技術的思想の範疇内において、各種の変更例または修正例に想到し得ることは明らかであり、これらについても、当然に本発明の技術的範囲に属するものと了解される。   As described above, the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to such examples. It is apparent that those skilled in the art to which the present invention pertains can conceive various changes or modifications within the scope of the technical idea described in the claims. It is understood that these also belong to the technical scope of the present invention.

1 リチウムイオン二次電池
10 正極層
10a 被覆粒子
11 正極活物質粒子
12 被覆層
20 負極層
21 負極活物質粒子
30 電解質層
31 固体電解質粒子

DESCRIPTION OF SYMBOLS 1 Lithium ion secondary battery 10 Positive electrode layer 10a Coating particles 11 Positive electrode active material particles 12 Coating layer 20 Negative electrode layer 21 Negative electrode active material particles 30 Electrolyte layer 31 Solid electrolyte particles

Claims (4)

複数の正極活物質一次粒子が凝集した正極活物質二次粒子、及び前記正極活物質二次粒子の表面の少なくとも一部を覆う被覆層を備える被覆粒子と、
前記被覆粒子に接触する固体電解質粒子と、を備え、
前記正極活物質二次粒子の平均粒径は、3.0〜10.0μmであり、
前記被覆層は、ランタン、イットリウム、セリウム、アルミニウム、ガリウム、インジウム、チタン、ジルコニウム及びニオブから選択されるいずれかとリチウムとを含む酸化物を含み、かつ、非晶質であり、
前記被覆層が、前記正極活物質二次粒子の外側を覆う層と、前記正極活物質二次粒子を構成する前記正極活物質一次粒子同士の空隙により構成される前記正極活物質二次粒子の内空隙を覆う層とを含むものであり、
前記被覆層に含まれる前記元素の合計モル数と前記正極活物質二次粒子内のリチウム以外の全金属元素の合計モル数との比が0.1〜3.0mol%であることを特徴とする、全固体リチウムイオン二次電池。
A plurality of positive electrode active material primary particles aggregated positive electrode active material secondary particles, and coated particles comprising a coating layer covering at least a part of the surface of the positive electrode active material secondary particles,
Solid electrolyte particles in contact with the coated particles,
The average particle diameter of the secondary particles of the positive electrode active material is 3.0 to 10.0 μm,
The coating layer includes an oxide containing lithium and any one selected from lanthanum, yttrium, cerium, aluminum, gallium, indium, titanium, zirconium, and niobium, and is amorphous.
The coating layer is a layer that covers the outside of the positive electrode active material secondary particles, and the positive electrode active material secondary particles that are configured by voids between the positive electrode active material primary particles that constitute the positive electrode active material secondary particles. And a layer covering the inner space,
The ratio between the total mole number of the elements contained in the coating layer and the total mole number of all metal elements other than lithium in the secondary particles of the positive electrode active material is 0.1 to 3.0 mol%. All-solid lithium-ion secondary battery.
前記正極活物質二次粒子は、以下の化学式1で示される正極活物質、及び以下の化学式2で示される正極活物質のうち、少なくとも一方を含むことを特徴とする、請求項1記載の全固体リチウムイオン二次電池。
LiNi1−y (1)
前記化学式1において、MはCo、Mn、AlおよびMgからなる群から選ばれる1種以上の元素であり、
x、yは、0.5<x<1.4、0.3<yを満たす値である。
LiNi2−y (2)
前記化学式2において、MはCoおよびMnからなる群から選ばれる1種以上の元素であり、x、yは、0.5<x<1.1、0.3<yを満たす値である。
The positive active material secondary particles, the positive electrode active material represented by the following chemical formula 1, and of the positive electrode active material represented by the following Formula 2, characterized in that it comprises at least one, No placement claim 1 Symbol All-solid lithium-ion secondary battery.
Li x Ni y M 1-y O 2 (1)
In Chemical Formula 1, M is one or more elements selected from the group consisting of Co, Mn, Al, and Mg;
x and y are values satisfying 0.5 <x <1.4 and 0.3 <y.
Li x Ni y M 2-y O 4 (2)
In Chemical Formula 2, M is one or more elements selected from the group consisting of Co and Mn, and x and y are values satisfying 0.5 <x <1.1 and 0.3 <y.
前記固体電解質粒子は、硫化物系固体電解質粒子であることを特徴とする、請求項1又は2に記載の全固体リチウムイオン二次電池。 The solid electrolyte particles are characterized by a sulfide-based solid electrolyte particles, solid-state lithium-ion secondary battery according to claim 1 or 2. 前記硫化物系固体電解質粒子は、ケイ素、リン、及びホウ素からなる群から選ばれる一種以上の元素を含有することを特徴とする、請求項記載の全固体リチウムイオン二次電池。 The all-solid lithium-ion secondary battery according to claim 3 , wherein the sulfide-based solid electrolyte particles contain one or more elements selected from the group consisting of silicon, phosphorus, and boron.
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