Solid electrolyte material and battery using the same

Abstract

A solid electrolyte material according to the present disclosure contains Li, Zr, Y, Cl, and O. The molar ratio of the O to the Y is greater than 0, but not greater than 0.60. A battery 1000 according to the present disclosure comprises a positive electrode 201, a negative electrode 203, and an electrolyte layer 202 provided between the positive electrode 201 and the negative electrode 203. At least one member selected from the group consisting of the positive electrode 201, the negative electrode 203, and the electrolyte layer 202 contains the solid electrolyte material.

Description

Technical Field

[0001] The present disclosure relates to a solid electrolyte material and a battery using the same.

Background Art

[0002] Patent Document 1 discloses an all-solid-state battery using a sulfide solid electrolyte. Patent Document 2 discloses a solid electrolyte material represented by Li 6-3z Y z X6 (where 0 < z < 2 is satisfied and X is Cl or Br).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure provides a novel solid electrolyte material with high utility.

Means for Solving the Problems

[0005] The solid electrolyte material of the present disclosure contains Li, Zr, Y, Cl, and O, and the molar ratio of O to Y is greater than 0 and not more than 0.60.

Effects of the Invention

[0006] According to the present disclosure, a novel solid electrolyte material with high utility can be realized.

Brief Description of the Drawings

[0007] [Figure 1] FIG. 1 shows a cross-sectional view of a battery 1000 according to the second embodiment. [Figure 2] FIG. 2 is a graph showing the X-ray diffraction patterns of the solid electrolyte materials according to Examples 1 to 3 and Reference Example 1. [Figure 3] FIG. 3 shows a schematic diagram of a pressing die 300 used to evaluate the ionic conductivity of a solid electrolyte material. [Figure 4] FIG. 4 is a graph showing a Cole-Cole plot obtained by measuring the impedance of the solid electrolyte material according to Example 1. [Figure 5] FIG. 5 is a graph showing the initial discharge characteristics of the batteries according to Example 1 and Reference Example 1. [Figure 6] FIG. 6 is a graph showing the results of thermal analysis of the solid electrolyte materials according to Examples 1 to 3 and Reference Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0009] (First embodiment) The solid electrolyte material according to the first embodiment contains Li, Zr, Y, Cl, and O, and the molar ratio of O to Y is greater than 0 and equal to or less than 0.60.

[0010] The solid electrolyte material according to the first embodiment is a novel, highly useful solid electrolyte material. The solid electrolyte material according to the first embodiment can have, for example, a practical lithium ion conductivity, for example, a high lithium ion conductivity. Here, the high lithium ion conductivity is, for example, 2.5×10 -4 That is, the solid electrolyte material according to the first embodiment has a specific resistance of, for example, 2.5×10 -4 It may have an ionic conductivity of 5 S / cm or more.

[0011] The solid electrolyte material according to the first embodiment can be used to obtain an all-solid-state battery having excellent charge-discharge characteristics. The all-solid-state battery may be a primary battery or a secondary battery.

[0012] It is desirable that the solid electrolyte material according to the first embodiment is substantially free of sulfur. The term "substantially free of sulfur" in the solid electrolyte material according to the first embodiment means that the solid electrolyte material does not contain sulfur as a constituent element, except for sulfur inevitably mixed in as an impurity. In this case, the amount of sulfur mixed in the solid electrolyte material as an impurity is, for example, 1 mol % or less. From the viewpoint of safety, it is desirable that the solid electrolyte material according to the first embodiment is free of sulfur. A sulfur-free solid electrolyte material is excellent in safety because it does not generate hydrogen sulfide even when exposed to the atmosphere. The sulfide solid electrolyte disclosed in Patent Document 1 may generate hydrogen sulfide when exposed to the atmosphere.

[0013] The solid electrolyte material according to the first embodiment may consist essentially of Li, Zr, Y, Cl, and O. "The solid electrolyte material according to the first embodiment consists essentially of Li, Zr, Y, Cl, and O" means that in the solid electrolyte material according to the first embodiment, the ratio (i.e., molar fraction) of the total amount of substance of Li, Zr, Y, Cl, and O to the total amount of substance of all elements constituting the solid electrolyte material is 90% or more. As an example, this ratio may be 95% or more. The solid electrolyte material according to the first embodiment may consist only of Li, Zr, Y, Cl, and O.

[0014] In order to increase the ionic conductivity of the solid electrolyte material, the molar ratio of O to Y in the solid electrolyte material according to the first embodiment may be greater than 0 and equal to or less than 0.55.

[0015] In order to increase the ionic conductivity of the solid electrolyte material, the molar ratio of O to Y in the solid electrolyte material according to the first embodiment may be greater than 0 and equal to or less than 0.50, or may be equal to or greater than 0.01 and equal to or less than 0.50.

[0016] In order to increase the ionic conductivity of the solid electrolyte material, the solid electrolyte material according to the first embodiment may further contain at least one selected from the group consisting of Mg, Ca, Zn, Sr, Ba, Al, Sc, Ga, Bi, La, Sm, Hf, Ta, and Nb.

[0017] The X-ray diffraction pattern of the solid electrolyte material according to the first embodiment can be obtained using Cu-Kα. The obtained X-ray diffraction pattern may have diffraction peaks in the following diffraction angle 2θ ranges: 15.5° to 16.0°, 16.7° to 16.9°, 17.5° to 17.7°, 20.1° to 20.3°, 22.3° to 22.5°, 31.4° to 31.6°, 35.5° to 35.8°, 46.9° to 47.2°, and 48.9° to 49.1°. Such a solid electrolyte material has high lithium ion conductivity.

[0018] The X-ray diffraction pattern of the solid electrolyte material according to the first embodiment can be obtained using Cu-Kα. The obtained X-ray diffraction pattern may have diffraction peaks in the following diffraction angle 2θ ranges: 15.5° to 15.7°, 16.7° to 16.9°, 17.5° to 17.7°, 20.1° to 20.3°, 22.3° to 22.5°, 31.4° to 31.6°, 35.6° to 35.8°, 47.0° to 47.2°, and 48.9° to 49.1°. Such a solid electrolyte material has high lithium ion conductivity.

[0019] A diffraction peak in an X-ray diffraction pattern is also simply called a "peak."

[0020] The X-ray diffraction pattern of the solid electrolyte material according to the first embodiment can be obtained by X-ray diffraction measurement by the θ-2θ method using Cu-Kα radiation (wavelengths of 1.5405 Å and 1.5444 Å, ie, wavelengths of 0.15405 nm and 0.15444 nm).

[0021] The peak angle is the angle at which the maximum intensity of the mountain-shaped part where the SN ratio is 3 or more and the half-width is 10° or less. The half-width is the maximum intensity of the peak. MAX When the intensity is I MAX The signal-to-noise ratio (SN ratio) is the ratio of the signal S to the background noise N.

[0022] To increase the ionic conductivity of the solid electrolyte material, the molar ratio of Zr to Y may be 0.7 or more and 1.1 or less.

[0023] To increase the ionic conductivity of the solid electrolyte material, the molar ratio of Li to Y may be 4.4 or more and 5.6 or less.

[0024] To increase the ionic conductivity of the solid electrolyte material, the molar ratio of Cl to Y may be 7.7 or more and 12.7 or less.

[0025] In order to increase the ionic conductivity of the solid electrolyte material, the molar ratio of Li to Y may be 4.4 or more and 5.6 or less, the molar ratio of Zr to Y may be 0.7 or more and 1.1 or less, and the molar ratio of Cl to Y may be 7.7 or more and 12.7 or less.

[0026] The molar ratio of Li to Y is calculated by the formula: (amount of substance of Li) / (amount of substance of Y). The molar ratio of Zr to Y is calculated by the formula: (amount of substance of Zr) / (amount of substance of Y). The molar ratio of Cl to Y is calculated by the formula: (amount of substance of Cl) / (amount of substance of Y). Hereinafter, the molar ratio of Li to Y may be expressed as "molar ratio x". The molar ratio of Zr to Y may be expressed as "molar ratio y". The molar ratio of Cl to Y may be expressed as "molar ratio z".

[0027] To further increase the ionic conductivity of the solid electrolyte material, the molar ratio x may be 4.97 or more and 5.02 or less, the molar ratio y may be 0.85 or more and 0.94 or less, and the molar ratio z may be 8.54 or more and 11.34 or less.

[0028] The shape of the solid electrolyte material according to the first embodiment is not limited. Examples of the shape include a needle shape, a sphere shape, or an oval sphere shape. The solid electrolyte material according to the first embodiment may be in the form of particles. The solid electrolyte material according to the first embodiment may be formed into the shape of a pellet or a plate.

[0029] For example, when the solid electrolyte material according to the first embodiment has a particulate (e.g., spherical) shape, the solid electrolyte material according to the first embodiment may have a median diameter of 0.1 μm or more and 100 μm or less. This allows the solid electrolyte material according to the first embodiment and other materials, such as active materials, to be dispersed well. The median particle diameter refers to the particle size (d50) corresponding to 50% cumulative volume in the volume-based particle size distribution. The volume-based particle size distribution can be measured using a laser diffraction measurement device or an image analysis device.

[0030] In order to increase the ionic conductivity of the solid electrolyte material according to the first embodiment and to disperse the solid electrolyte material according to the first embodiment and the active material well, the median diameter may be 0.5 μm or more and 10 μm or less.

[0031] In order to disperse the solid electrolyte material according to the first embodiment and the active material better, the solid electrolyte material according to the first embodiment may have a smaller median diameter than the active material.

[0032] <Method of manufacturing solid electrolyte material> The solid electrolyte material according to the first embodiment can be produced by the following method.

[0033] First, raw material powders of halides are prepared and mixed to have a desired composition.

[0034] For example, when synthesizing a solid electrolyte material consisting of Li, Zr, Y, Cl, and O, YCl3 raw material powder, LiCl raw material powder, and ZrCl4 raw material powder are mixed. The resulting mixed powder is fired in an inert gas atmosphere (e.g., an argon atmosphere with a dew point of -60°C or less) in which the oxygen and moisture concentrations are adjusted. The firing temperature may be, for example, in the range of 200°C or more and 650°C or less.

[0035] The resulting reactant is left standing in an atmosphere with a relatively high dew point (for example, an argon atmosphere with a dew point of -30°C), and then baked at a temperature above the melting point (for example, 550°C).

[0036] The raw material powders may be mixed in a predetermined molar ratio to offset compositional changes that may occur during the synthesis process. The amount of oxygen in the solid electrolyte material is determined by selecting the raw material powders, the oxygen concentration in the atmosphere, the water concentration in the atmosphere, and the reaction time. In this way, the desired solid electrolyte material is obtained.

[0037] The fired product obtained in the first firing may be used as the solid electrolyte material according to the first embodiment.

[0038] It is believed that the oxygen contained in the solid electrolyte material according to the first embodiment is taken in from the atmosphere having the above-mentioned relatively high dew point.

[0039] The composition of the solid electrolyte material can be determined by, for example, inductively coupled plasma optical emission spectroscopy, ion chromatography, or non-dispersive infrared spectroscopy. For example, the composition of Li, Zr, and Y can be determined by inductively coupled plasma optical emission spectroscopy, the composition of Cl can be determined by ion chromatography, and O can be measured by non-dispersive infrared spectroscopy.

[0040] (Second embodiment) The second embodiment will be described below, and the matters described in the first embodiment will be omitted as appropriate.

[0041] In the second embodiment, a battery using the solid electrolyte material according to the first embodiment will be described.

[0042] The battery according to the second embodiment includes a positive electrode, a negative electrode, and an electrolyte layer. The electrolyte layer is disposed between the positive electrode and the negative electrode. At least one selected from the group consisting of the positive electrode, the electrolyte layer, and the negative electrode contains the solid electrolyte material according to the first embodiment.

[0043] The battery according to the second embodiment has excellent charge / discharge characteristics because it contains the solid electrolyte material according to the first embodiment.

[0044] FIG. 1 shows a cross-sectional view of a battery 1000 according to a second embodiment.

[0045] The battery 1000 includes a positive electrode 201, an electrolyte layer 202, and a negative electrode 203. The electrolyte layer 202 is disposed between the positive electrode 201 and the negative electrode 203.

[0046] The positive electrode 201 contains positive electrode active material particles 204 and solid electrolyte particles 100 .

[0047] The electrolyte layer 202 contains an electrolyte material, such as a solid electrolyte material.

[0048] The negative electrode 203 contains negative electrode active material particles 205 and solid electrolyte particles 100 .

[0049] The solid electrolyte particles 100 are particles containing the solid electrolyte material according to the first embodiment. The solid electrolyte particles 100 may be particles made of the solid electrolyte material according to the first embodiment, or particles containing the solid electrolyte material according to the first embodiment as a main component. Here, particles containing the solid electrolyte material according to the first embodiment as a main component refer to particles in which the component contained most abundantly in terms of molar ratio is the solid electrolyte material according to the first embodiment.

[0050] The positive electrode 201 contains a material capable of absorbing and releasing metal ions (for example, lithium ions). The positive electrode 201 contains, for example, a positive electrode active material (for example, positive electrode active material particles 204).

[0051] Examples of the positive electrode active material include a lithium-containing transition metal oxide, a transition metal fluoride, a polyanionic material, a fluorinated polyanionic material, a transition metal sulfide, a transition metal oxyfluoride, a transition metal oxysulfide, or a transition metal oxynitride. An example of a lithium-containing transition metal oxide is LiNi 1-d-f Co d Al f O2 (where 0 <d、0<f、かつ0<(d+f)<1)またはLiCoO2である。

[0052] In order to ensure good dispersion of the positive electrode active material particles 204 and the solid electrolyte particles 100 in the positive electrode 201, the positive electrode active material particles 204 may have a median diameter of 0.1 μm or more. This good dispersion improves the charge / discharge characteristics of the battery. In order to ensure rapid diffusion of lithium within the positive electrode active material particles 204, the positive electrode active material particles 204 may have a median diameter of 100 μm or less. The rapid diffusion of lithium allows the battery to operate at high output. As described above, the positive electrode active material particles 204 may have a median diameter of 0.1 μm or more and 100 μm or less.

[0053] In order to disperse the positive electrode active material particles 204 and the solid electrolyte particles 100 well in the positive electrode 201 , the positive electrode active material particles 204 may have a larger median diameter than the solid electrolyte particles 100 .

[0054] To increase the energy density and output of the battery 1000, the ratio of the volume of the positive electrode active material particles 204 to the total volume of the positive electrode active material particles 204 and the solid electrolyte particles 100 in the positive electrode 201 may be 0.30 or more and 0.95 or less.

[0055] To increase the energy density and power output of the battery 1000, the positive electrode 201 may have a thickness of 10 μm or more and 500 μm or less.

[0056] The electrolyte layer 202 contains an electrolyte material. The electrolyte material may be the solid electrolyte material according to the first embodiment. The electrolyte layer 202 may be a solid electrolyte layer.

[0057] The electrolyte layer 202 may be made of only the solid electrolyte material according to the first embodiment, or may be made of only a solid electrolyte material different from the solid electrolyte material according to the first embodiment.

[0058] Examples of solid electrolyte materials different from the solid electrolyte material according to the first embodiment include Li2MgX'4, Li2FeX'4, Li(Al,Ga,In)X'4, Li3(Al,Ga,In)X'6, or LiI, where X' is at least one selected from the group consisting of F, Cl, Br, and I.

[0059] In the present disclosure, the notation "(A, B, C)" in a chemical formula means "at least one selected from the group consisting of A, B, and C." For example, "(Al, Ga, In)" is synonymous with "at least one selected from the group consisting of Al, Ga, and In."

[0060] Hereinafter, the solid electrolyte material according to the first embodiment will be referred to as a first solid electrolyte material, and a solid electrolyte material different from the solid electrolyte material according to the first embodiment will be referred to as a second solid electrolyte material.

[0061] The electrolyte layer 202 may contain not only the first solid electrolyte material but also the second solid electrolyte material. The first solid electrolyte material and the second solid electrolyte material may be uniformly dispersed. A layer made of the first solid electrolyte material and a layer made of the second solid electrolyte material may be stacked along the stacking direction of the battery 1000.

[0062] In order to prevent short circuits between the positive electrode 201 and the negative electrode 203 and to increase the output of the battery, the electrolyte layer 202 may have a thickness of 1 μm or more and 100 μm or less.

[0063] The negative electrode 203 contains a material capable of absorbing and releasing metal ions (for example, lithium ions) and a negative electrode active material (for example, negative electrode active material particles 205).

[0064] Examples of the negative electrode active material include a metal material, a carbon material, an oxide, a nitride, a tin compound, or a silicon compound. The metal material may be a simple metal or an alloy. An example of the metal material is lithium metal or a lithium alloy. Examples of the carbon material are natural graphite, coke, partially graphitized carbon, carbon fiber, spherical carbon, artificial graphite, or amorphous carbon. From the viewpoint of capacity density, suitable examples of the negative electrode active material are silicon (i.e., Si), tin (i.e., Sn), a silicon compound, or a tin compound.

[0065] In the negative electrode 203, in order to disperse the negative electrode active material particles 205 and the solid electrolyte particles 100 well, the negative electrode active material particles 205 may have a median diameter of 0.1 μm or more. This good dispersion improves the charge / discharge characteristics of the battery. In order to rapidly diffuse lithium within the negative electrode active material particles 205, the negative electrode active material particles 205 may have a median diameter of 100 μm or less. Due to the rapid diffusion of lithium, the battery can operate at a high output. As described above, the negative electrode active material particles 205 may have a median diameter of 0.1 μm or more and 100 μm or less.

[0066] In order to disperse the negative electrode active material particles 205 and the solid electrolyte particles 100 well in the negative electrode 203 , the negative electrode active material particles 205 may have a larger median diameter than the solid electrolyte particles 100 .

[0067] In order to increase the energy density and output of the battery 1000, in the negative electrode 203, the ratio of the volume of the negative electrode active material particles 205 to the total volume of the negative electrode active material particles 205 and the solid electrolyte particles 100 may be 0.30 or more and 0.95 or less.

[0068] To increase the energy density and power output of the battery 1000, the negative electrode 203 may have a thickness of 10 μm or more and 500 μm or less.

[0069] In order to enhance ionic conductivity, chemical stability, and electrochemical stability, at least one selected from the group consisting of the positive electrode 201, the electrolyte layer 202, and the negative electrode 203 may contain a second solid electrolyte material.

[0070] The second solid electrolyte material may be a halide solid electrolyte.

[0071] Examples of halide solid electrolytes are Li2MgX'4, Li2FeX'4, Li(Al,Ga,In)X'4, Li3(Al,Ga,In)X'6, or LiI, where X' is at least one selected from the group consisting of F, Cl, Br, and I.

[0072] The second solid electrolyte material may be a sulfide solid electrolyte.

[0073] Examples of sulfide solid electrolytes are Li2S-P2S5, Li2S-SiS2, Li2S-B2S3, Li2S-GeS2, Li 3.25 Ge 0.25 P 0.75 S4, or Li 10 GeP2S 12 is.

[0074] The second solid electrolyte material may be an oxide solid electrolyte.

[0075] Examples of oxide solid electrolytes include: (i) NASICON-type solid electrolytes such as LiTi2(PO4)3 or its elemental substitutes; (ii) Perovskite-type solid electrolytes such as (LaLi)TiO3; (iii) Li 14 ZnGeO 16 LISICON-type solid electrolytes such as Li4SiO4, LiGeO4, or elemental substitutions thereof; (iv) Li7La3Zr2O 12 or a garnet-type solid electrolyte such as an element substitution product thereof; or (v) Li3PO4 or its N-substituted derivatives is.

[0076] The second solid electrolyte material may be an organic polymer solid electrolyte.

[0077] Examples of organic polymer solid electrolytes include polymer compounds and lithium salt compounds. The polymer compounds may have an ethylene oxide structure. Polymer compounds having an ethylene oxide structure can contain a large amount of lithium salt, thereby further increasing ionic conductivity.

[0078] Examples of lithium salts include LiPF, LiBF, LiSbF, LiAsF, LiSOCF, LiN(SOCF), LiN(SOCF) , LiN(SOCF)(SOCF), or LiC(SOCF). One lithium salt selected from these may be used alone. Alternatively, a mixture of two or more lithium salts selected from these may be used.

[0079] At least one selected from the group consisting of the positive electrode 201, the electrolyte layer 202, and the negative electrode 203 may contain a non-aqueous electrolyte, a gel electrolyte, or an ionic liquid in order to facilitate the exchange of lithium ions and improve the output characteristics of the battery 1000.

[0080] The non-aqueous electrolyte contains a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent.

[0081] Examples of non-aqueous solvents include cyclic carbonate ester solvents, chain carbonate ester solvents, cyclic ether solvents, chain ether solvents, cyclic ester solvents, chain ester solvents, and fluorine-containing solvents. Examples of cyclic carbonate ester solvents include ethylene carbonate, propylene carbonate, and butylene carbonate. Examples of chain carbonate ester solvents include dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate. Examples of cyclic ether solvents include tetrahydrofuran, 1,4-dioxane, and 1,3-dioxolane. Examples of chain ether solvents include 1,2-dimethoxyethane and 1,2-diethoxyethane. Examples of cyclic ester solvents include γ-butyrolactone. Examples of chain ester solvents include methyl acetate. Examples of fluorine-containing solvents include fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, and fluorodimethylene carbonate.

[0082] One non-aqueous solvent selected from these may be used alone, or a mixture of two or more non-aqueous solvents selected from these may be used.

[0083] Examples of lithium salts include LiPF, LiBF, LiSbF, LiAsF, LiSOCF, LiN(SOCF), LiN(SOCF) , LiN(SOCF)(SOCF), or LiC(SOCF). One lithium salt selected from these may be used alone. Alternatively, a mixture of two or more lithium salts selected from these may be used.

[0084] The concentration of the lithium salt is, for example, in the range of 0.5 mol / liter to 2 mol / liter.

[0085] The gel electrolyte may be a polymer material impregnated with a non-aqueous electrolyte, such as polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, or a polymer having an ethylene oxide bond.

[0086] Examples of cations contained in ionic liquids are: (i) aliphatic chain quaternary salts such as tetraalkylammonium or tetraalkylphosphonium; (ii) aliphatic cyclic ammoniums such as pyrrolidiniums, morpholiniums, imidazoliniums, tetrahydropyrimidiniums, piperaziniums, or piperidiniums, or (iii) Nitrogen-containing heterocyclic aromatic cations such as pyridiniums or imidazoliums.

[0087] An example of an anion found in ionic liquids is PF6 - , BF4 - , SbF6 - , AsF6 - , SO3CF3 - , N(SO2CF3)2 - , N(SO2C2F5)2 - , N(SO2CF3)(SO2C4F9) - , or C(SO2CF3)3 - is.

[0088] The ionic liquid may contain a lithium salt.

[0089] At least one selected from the group consisting of the positive electrode 201, the electrolyte layer 202, and the negative electrode 203 may contain a binder for the purpose of improving adhesion between particles.

[0090] Examples of binders include polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polymethyl ester of acrylic acid, polyethyl ester of acrylic acid, polyhexyl ester of acrylic acid, polymethacrylic acid, polymethyl ester of methacrylic acid, polyethyl ester of methacrylic acid, polyhexyl ester of methacrylic acid, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropolypropylene, styrene-butadiene rubber, and carboxymethyl cellulose. Copolymers can also be used as binders. Examples of such binders include copolymers of two or more materials selected from the group consisting of tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, and hexadiene. Mixtures of two or more materials selected from these may also be used as binders.

[0091] At least one selected from the positive electrode 201 and the negative electrode 203 may contain a conductive additive to enhance electronic conductivity.

[0092] Examples of the conductive additive include: (i) graphites such as natural or synthetic graphite; (ii) carbon blacks such as acetylene black or ketjen black; (iii) conductive fibers such as carbon or metal fibers; (iv) fluorocarbons, (v) metal powders such as aluminum; (vi) conductive whiskers such as zinc oxide or potassium titanate; (vii) a conductive metal oxide, such as titanium oxide, or (viii) Conductive polymer compounds such as polyaniline, polypyrrole, or polythiophene From the viewpoint of cost reduction, the above (i) or (ii) may be used.

[0093] Examples of the shape of the battery according to the second embodiment include a coin type, a cylindrical type, a square type, a sheet type, a button type, a flat type, and a laminate type.

[0094] The battery according to the second embodiment may be manufactured, for example, by preparing a material for forming a positive electrode, a material for forming an electrolyte layer, and a material for forming a negative electrode, and by using a known method to fabricate a laminate in which the positive electrode, the electrolyte layer, and the negative electrode are arranged in this order. [Example]

[0095] Hereinafter, the present disclosure will be described in more detail with reference to examples and reference examples.

[0096] Example 1 [Preparation of solid electrolyte materials] In an argon atmosphere having a dew point of -60°C or less and an oxygen concentration of 0.1% by volume or less (hereinafter referred to as a "dry argon atmosphere"), raw material powders of YCl3, ZrCl4, and LiCl were prepared in a molar ratio of approximately YCl3:ZrCl4:LiCl = 1:1:5. These raw material powders were ground and mixed in a mortar. The resulting mixture was fired at 550°C for 2 hours in a sealed SUS container in a dry argon atmosphere, and then ground in the mortar. In this way, a solid electrolyte material according to Example 1 was obtained.

[0097] [Composition analysis of solid electrolyte materials] The Li and Y contents per unit weight of the solid electrolyte material according to Example 1 were measured by high-frequency inductively coupled plasma atomic emission spectroscopy using a high-frequency inductively coupled plasma optical emission spectrometer (iCAP7400, manufactured by Thermo Fisher Scientific). The Cl content of the solid electrolyte material according to Example 1 was measured by ion chromatography using an ion chromatograph (ICS-2000, manufactured by Dionex). Based on the Li, Zr, Y, and Cl contents obtained from these measurement results, the molar ratio of Li:Zr:Y:Cl was calculated. As a result, the solid electrolyte material according to Example 1 had a Li:Zr:Y:Cl molar ratio of 5.00:0.94:1.0:11.34.

[0098] The mass of O relative to the total mass of the solid electrolyte material according to Example 1 was measured by non-dispersive infrared absorption spectroscopy using an oxygen / nitrogen / hydrogen analyzer (EMGA-930, manufactured by Horiba, Ltd.). As a result, the mass of O relative to the total mass of the solid electrolyte material according to Example 1 was 0.02%. Based on this, the molar ratio of O to Y was calculated. As a result, the molar ratio of O to Y in the solid electrolyte material according to Example 1 was 0.01.

[0099] In the compositional analysis, elements with a mole fraction less than 0.01% relative to Y were considered as impurities.

[0100] [Melt point measurement] A thermal analyzer (Q1000, manufactured by TA Instruments) was used to measure the melting point. In a nitrogen atmosphere, approximately 5 mg of the solid electrolyte material according to Example 1 was weighed and heated from room temperature to 550°C at a heating rate of 10 K / min. An endothermic peak was observed at this time. Based on the obtained data, a two-dimensional graph was created with temperature on the horizontal axis and the calorific value on the vertical axis. Two points on the graph where the solid electrolyte material neither generated nor absorbed heat were connected by a straight line, and this was used as the baseline. The melting point was then determined as the intersection of the tangent to the inflection point of the endothermic peak and the baseline. As a result, the melting point of the solid electrolyte material according to Example 1 was 477.1°C. FIG. 6 is a graph showing the results of thermal analysis of the solid electrolyte material according to Example 1.

[0101] [X-ray diffraction] The X-ray diffraction pattern of the solid electrolyte material according to Example 1 was measured using an X-ray diffractometer (RIGAKU, MiniFlex600) in a dry environment with a dew point of −45° C. or less. Cu-Kα radiation (wavelengths 1.5405 Å and 1.5444 Å) was used as the X-ray source.

[0102] As a result of X-ray diffraction measurement, peaks were present at 15.66°, 16.73°, 17.57°, 20.21°, 22.36°, 31.47°, 35.75°, 47.09°, and 49.00° in the X-ray diffraction pattern of the solid electrolyte material according to Example 1. Figure 2 is a graph showing the X-ray diffraction pattern of the solid electrolyte material according to Example 1.

[0103] [Evaluation of ionic conductivity] FIG. 3 shows a schematic diagram of a pressing die 300 used to evaluate the ionic conductivity of a solid electrolyte material.

[0104] The pressure molding die 300 had an upper punch 301, a frame 302, and a lower punch 303. The frame 302 was made of insulating polycarbonate. The upper punch 301 and the lower punch 303 were both made of electronically conductive stainless steel.

[0105] Using the pressure molding die 300 shown in FIG. 3, the ionic conductivity of the solid electrolyte material of Example 1 was measured by the following method.

[0106] In a dry argon atmosphere, powder 101 of the solid electrolyte material according to Example 1 was filled into a pressure molding die 300. Inside the pressure molding die 300, a pressure of 300 MPa was applied to powder 101 of the solid electrolyte material according to Example 1 using an upper punch 301.

[0107] While the pressure was still applied, the impedance of the solid electrolyte material according to Example 1 was measured at room temperature by electrochemical impedance measurement using a potentiostat (Princeton Applied Research, VersaSTAT4) via the upper punch 301 and the lower punch 303. Although not shown, a working electrode and a potential measurement terminal were connected to the upper punch 301, and a counter electrode and a reference electrode were connected to the lower punch 303.

[0108] FIG. 4 is a graph showing a Cole-Cole plot obtained by measuring the impedance of the solid electrolyte material according to Example 1.

[0109] 4, the real value of the impedance at the measurement point where the absolute value of the phase of the complex impedance is smallest was considered to be the resistance value for ion conduction of the solid electrolyte material according to Example 1. The real value is indicated by the arrow R SE Using the resistance value, the ionic conductivity was calculated based on the following formula (1). σ=(R SE ×S / t) -1 ···(1) where σ is the ionic conductivity, S is the contact area of ​​the solid electrolyte material with the punch upper portion 301 (equal to the cross-sectional area of ​​the hollow portion of the frame mold 302 in FIG. 3), and R SEis the resistance value of the solid electrolyte material in the impedance measurement, and t is the thickness of the solid electrolyte material to which pressure is applied (equal to the thickness of the layer formed from the powder 101 of the solid electrolyte material in FIG. 3).

[0110] The ionic conductivity of the solid electrolyte material according to Example 1 measured at 25°C was 1.2 × 10 -3 S / cm.

[0111] [Battery construction] In a dry argon atmosphere, the solid electrolyte material according to Example 1 and LiCoO2 as an active material were prepared in a volume ratio of 70:30. These materials were mixed in an agate mortar to obtain a mixture.

[0112] In an insulating cylinder having an inner diameter of 9.5 mm, the solid electrolyte material (100 mg) from Example 1, the above-mentioned mixture (10.0 mg), and aluminum powder (14.7 mg) were layered in this order to obtain a laminate. A pressure of 300 MPa was applied to the laminate to form a positive electrode and a solid electrolyte layer. The solid electrolyte layer had a thickness of 500 μm.

[0113] Next, a metal In foil was laminated on the solid electrolyte layer. The solid electrolyte layer was sandwiched between the metal In foil and the positive electrode. The metal In foil had a thickness of 200 μm. Next, a pressure of 80 MPa was applied to the metal In foil to form the negative electrode.

[0114] Current collectors made of stainless steel were attached to the positive and negative electrodes, and then current collecting leads were attached to the current collectors. Finally, an insulating ferrule was used to isolate the inside of the insulating cylinder from the outside atmosphere and seal the inside of the cylinder. In this way, a battery according to Example 1 was obtained.

[0115] [Charge / discharge test] The battery according to Example 1 was placed in a thermostatic chamber at 25°C. 2The battery according to Example 1 was charged at a current density of 86 μA / cm 2 until a voltage of 3.7 V was reached, which corresponds to a 0.05 C rate. 2 The battery according to Example 1 was discharged at a current density of 0.1 V until a voltage of 1.9 V was reached.

[0116] As a result of the charge-discharge test, the battery according to Example 1 had an initial discharge capacity of 723 μAh.

[0117] FIG. 5 is a graph showing the initial discharge characteristics of the battery according to Example 1.

[0118] <Examples 2 and 3> In Example 2, the solid electrolyte material of Example 1 was left standing for about 10 minutes in an atmosphere having a dew point of -30°C and an oxygen concentration of 20.9% by volume or less. The reactant was then fired in a dry argon atmosphere in a SUS sealed container at 550°C for 1 hour, and then pulverized in a mortar. In this way, the solid electrolyte material of Example 2 was obtained.

[0119] In Example 3, the solid electrolyte material according to Example 3 was obtained in the same manner as in Example 2, except that the time during which the reactants were allowed to stand in an atmosphere having a dew point of -30°C and an oxygen concentration of 20.9% by volume or less was set to 90 minutes instead of approximately 10 minutes.

[0120] The element ratios (molar ratios), melting points, X-ray diffraction, and ionic conductivity of the solid electrolyte materials of Examples 2 and 3 were measured in the same manner as in Example 1. The measurement results are shown in Tables 1 and 2. FIG. 2 is a graph showing the X-ray diffraction patterns of the solid electrolyte materials of Examples 2 and 3. FIG. 6 is a graph showing the results of thermal analysis of the solid electrolyte materials of Examples 2 and 3.

[0121] The mass of O relative to the total mass of the solid electrolyte materials according to Examples 2 and 3 was 0.16% and 1.48%, respectively.

[0122] Using the solid electrolyte materials of Examples 2 and 3, the batteries of Examples 2 and 3 were obtained in the same manner as in Example 1.

[0123] A charge-discharge test was carried out using the batteries according to Examples 2 and 3 in the same manner as in Example 1. The batteries according to Examples 2 and 3 were charged and discharged satisfactorily, similar to the battery according to Example 1.

[0124] <Reference example 1> A solid electrolyte material according to Reference Example 1 was obtained in the same manner as in Example 2, except that the time during which the reactants were allowed to stand in an atmosphere having a dew point of -30°C and an oxygen concentration of 20.9% by volume or less was changed from approximately 10 minutes to 540 minutes.

[0125] The element ratio (molar ratio), melting point, X-ray diffraction, and ionic conductivity of the solid electrolyte material of Reference Example 1 were measured in the same manner as in Example 1. The measurement results are shown in Tables 1 and 2. FIG. 2 is a graph showing the X-ray diffraction pattern of the solid electrolyte material of Reference Example 1. FIG. 6 is a graph showing the results of thermal analysis of the solid electrolyte material of Reference Example 1. It should be noted that the melting point of the solid electrolyte material of Reference Example 1 could not be measured.

[0126] The mass of O relative to the total mass of the solid electrolyte material of Reference Example 1 was 2.87%.

[0127] Using the solid electrolyte material of Reference Example 1, a battery of Reference Example 1 was obtained in the same manner as in Example 1.

[0128] A charge / discharge test was carried out using the battery of Reference Example 1 in the same manner as in Example 1. The battery of Reference Example 1 was neither charged nor discharged. Figure 5 is a graph showing the initial discharge characteristics of the battery of Reference Example 1.

[0129] <Reference example 2> As Reference Example 2, the ionic conductivity of a solid electrolyte material consisting of Li, Y, Cl, and O, in which the molar ratio of O to Y satisfies the range of more than 0 and not more than 0.50, was confirmed. The solid electrolyte material of the Reference Example was produced by the following method.

[0130] In an argon atmosphere having a dew point of −60°C or less and an oxygen concentration of 0.1% by volume or less, raw material powders of YCl3 and LiCl were prepared in a molar ratio of 1:3. These raw material powders were ground and mixed in a mortar. The resulting mixture was fired in an alumina crucible at 550°C for 1 hour and then ground in the mortar. The resulting reactant was allowed to stand for approximately 10 minutes in an argon atmosphere having a dew point of −30°C and an oxygen concentration of 20.9% by volume. It was then fired at 550°C for 1 hour in an argon atmosphere having a dew point of −60°C or less and an oxygen concentration of 0.1% by volume or less, and then ground in the mortar. In this manner, a solid electrolyte material according to Reference Example 2 was obtained.

[0131] The element ratio (molar ratio) and ionic conductivity of the solid electrolyte material of Reference Example 2 were measured in the same manner as in Example 1. The measurement results are shown in Table 1. The mass of O relative to the total mass of the solid electrolyte material of Reference Example 2 was 0.22%.

[0132] [Table 1]

[0133] [Table 2]

[0134] <Consideration> As is clear from Table 1, the solid electrolyte materials according to Examples 1 to 3 exhibited a thermal conductivity of 2.5×10 -4The solid electrolyte materials according to Examples 1 to 3 have a high ionic conductivity of 100 S / cm or more. The solid electrolyte materials according to Examples 1 to 3 have a higher ionic conductivity than the solid electrolyte material according to Reference Example 1. Furthermore, the solid electrolyte materials according to Examples 1 to 3 have a higher ionic conductivity than the solid electrolyte material according to Reference Example 2, which does not contain zirconium.

[0135] As is clear from Table 1, the melting point increased as the molar ratio of O to Y increased. In other words, the higher the molar ratio, the higher the heat resistance of the material. On the other hand, as is clear from Reference Example 1, if the molar ratio is too high, the ionic conductivity of the solid electrolyte material decreases significantly.

[0136] The batteries according to Examples 1 to 3 were charged and discharged at 25°C.

[0137] The solid electrolyte materials according to Examples 1 to 3 do not contain sulfur and therefore do not generate hydrogen sulfide.

[0138] As described above, the solid electrolyte material according to the present disclosure has practical lithium ion conductivity and is suitable for providing a battery that can be charged and discharged well. [Industrial Applicability]

[0139] The solid electrolyte material of the present disclosure is used, for example, in an all-solid-state lithium-ion secondary battery. [Explanation of symbols]

[0140] 100 solid electrolyte particles 101 Solid electrolyte material powder 201 Positive electrode 202 Electrolyte layer 203 Negative electrode 204 Positive electrode active material particles 205 Negative electrode active material particles 300 pressure forming die 301 Frame type 302 Punch bottom 303 Punch top 1000 batteries

Claims

1. comprising Li, Zr, Y, Cl, and O; the molar ratio of O to Y is 0.06 or more and 0.60 or less; the molar ratio of Zr to Y is 0.7 or more and 0.94 or less; Solid electrolyte material.

2. the molar ratio of O to Y is 0.50 or less; The solid electrolyte material according to claim 1 .

3. Further comprising at least one selected from the group consisting of Mg, Ca, Zn, Sr, Ba, Al, Sc, Ga, Bi, La, Sm, Hf, Ta, and Nb; The solid electrolyte material according to claim 1 or 2.

4. In an X-ray diffraction pattern obtained by X-ray diffraction measurement using Cu—Kα, peaks are present in each of the following diffraction angle 2θ ranges: 15.5° or more and 16.0° or less, 16.7° or more and 16.9° or less, 17.5° or more and 17.7° or less, 20.1° or more and 20.3° or less, 22.3° or more and 22.5° or less, 31.4° or more and 31.6° or less, 35.5° or more and 35.8° or less, 46.9° or more and 47.2° or less, and 48.9° or more and 49.1° or less. The solid electrolyte material according to claim 1 .

5. In an X-ray diffraction pattern obtained by X-ray diffraction measurement using Cu—Kα, peaks are present in each of the following diffraction angle 2θ ranges: 15.5° or more and 15.7° or less, 16.7° or more and 16.9° or less, 17.5° or more and 17.7° or less, 20.1° or more and 20.3° or less, 22.3° or more and 22.5° or less, 31.4° or more and 31.6° or less, 35.6° or more and 35.8° or less, 47.0° or more and 47.2° or less, and 48.9° or more and 49.1° or less. The solid electrolyte material according to claim 4.

6. A positive electrode and a negative electrode; an electrolyte layer provided between the positive electrode and the negative electrode, At least one selected from the group consisting of the positive electrode, the negative electrode, and the electrolyte layer contains the solid electrolyte material according to any one of claims 1 to 5. battery.

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