Solid electrolyte material and battery using the same

Abstract

A solid electrolyte material composed of Li, Y, X, and O, where X is one selected from F, Cl, Br, and I, and the molar ratio of O to Y is greater than 0.01 and less than 0.52.

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 X 6 (where 0 < z < 2 and X is Cl or Br).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2011-129312

[0006] Patent Document 2: WO 2018 / 025582 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] An object of the present disclosure is to provide a solid electrolyte material having a low melting point and high ionic conductivity.

[0009] Means for Solving the Problems

[0010] The solid electrolyte material of the present disclosure is composed of Li, Y, X, and O, where X is one selected from F, Cl, Br, and I, and the molar ratio of O to Y is greater than 0.01 and less than 0.52.

[0011] Advantages of the Invention

[0012] The present disclosure provides a solid electrolyte material having a low melting point and high ionic conductivity. Brief Description of the Drawings

[0013] Figure 1 A cross-sectional view of the battery 1000 showing the second embodiment.

[0014] Figure 2 A diagram showing X-ray diffraction patterns of the solid electrolyte materials of Examples 1 to 3 and Comparative Example 1.

[0015] Figure 3 A schematic diagram showing the compression molding die 300 used for evaluating the ionic conductivity of the solid electrolyte material.

[0016] Figure 4 A diagram showing a Cole-Cole plot of the impedance measurement results of the solid electrolyte material of Example 1.

[0017] Figure 5 It is a graph showing the initial discharge characteristics of the battery of Example 1.

[0018] Figure 6 It is a graph showing the results of thermal analysis of Examples 1 to 3 and Comparative Example 1.

[0019] Figure 7 It is a graph showing the X-ray diffraction patterns of the solid electrolyte materials of Examples 4 to 6 and Comparative Examples 1 and 2.

[0020] Figure 8 It is a graph showing the Cole-Cole plot of the impedance measurement results of the solid electrolyte material of Example 4.

[0021] Figure 9 It is a graph showing the initial discharge characteristics of the battery of Example 4.

[0022] Figure 10 It is a graph showing the results of thermal analysis of Examples 4 to 6 and Comparative Examples 1 and 2. Detailed implementation mode

[0023] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0024] (First Embodiment)

[0025] The solid electrolyte material of the first embodiment is composed of Li, Y, X, and O. Among them, X is one selected from F, Cl, Br, and I. The molar ratio of O to Y is greater than 0.01 and less than 0.52. The solid electrolyte material of the first embodiment has a low melting point. Furthermore, the solid electrolyte material of the first embodiment has a high lithium ion conductivity. Among them, the so-called low melting point is, for example, 504°C or lower. That is, the solid electrolyte material of the first embodiment can have a melting point of 504°C or lower, for example. When the solid electrolyte material is a multiphase material, the melting point of the solid electrolyte material refers to the highest temperature among the melting points possessed by the solid electrolyte material. In addition, the so-called high lithium ion conductivity is, for example, 1×10 -5 S / cm or more. That is, the solid electrolyte material of the first embodiment can have a melting point of 504°C or lower and an ionic conductivity of 1×10 -5 S / cm or more, for example.

[0026] The solid electrolyte material of the first embodiment can be used to obtain an all-solid-state battery with excellent charge and discharge characteristics. The all-solid-state battery can be a primary battery or a secondary battery.

[0027] The solid electrolyte material of the first embodiment preferably does not contain sulfur. The sulfur-free solid electrolyte material does not generate hydrogen sulfide even when exposed to the atmosphere, and thus has excellent safety. The sulfide solid electrolyte disclosed in Patent Document 1 can generate hydrogen sulfide when exposed to the atmosphere.

[0028] The solid electrolyte material of the first embodiment may also be made of only Li, Y, X, and O.

[0029] In order to improve the ionic conductivity of the solid electrolyte material, the solid electrolyte material of the first embodiment may further contain at least one selected from Mg, Ca, Zn, Sr, Ba, Al, Sc, Ga, Bi, La, Zr, Hf, Ta, and Nb.

[0030] The transition metal contained in the solid electrolyte material of this embodiment may be only Y except for the elements contained as inevitable impurities.

[0031] X may also be Cl. Such a solid electrolyte material has a low melting point and high ionic conductivity.

[0032] Hereinafter, a first example and a second example of the solid electrolyte material of the first embodiment will be described. The first example of the solid electrolyte material of the first embodiment is described as "the first solid electrolyte material", and the second example of the solid electrolyte material of the first embodiment is described as "the second solid electrolyte material".

[0033] (The first solid electrolyte material)

[0034] The X-ray diffraction pattern of the first solid electrolyte material can be measured using Cu-Kα rays. In the obtained X-ray diffraction pattern, peaks may also exist in the range of diffraction angle 2θ of 15.2° to 16.4°, 16.7° to 18.6°, 30.8° to 31.9°, 33.2° to 34.3°, 40.3° to 41.4°, 48.2° to 49.3°, and 53.0° to 54.2°. Such a solid electrolyte material has a low melting point and high ionic conductivity.

[0035] In order to lower the melting point of the solid electrolyte material, the molar ratio of Li to Y may be 2.2 to 2.56, and the molar ratio of X to Y may be 3.5 to 5.9.

[0036] In order to further lower the melting point of the solid electrolyte material, the molar ratio of Li to Y may be 2.49 to 2.56, and the molar ratio of X to Y may be 3.91 to 5.29.

[0037] The molar ratio of O to Y may also be, for example, 1.0 or less.

[0038] The upper limit value and the lower limit value of the molar ratio of O to Y can be defined by any combination selected from the values of 0.01, 0.04, 0.23, and 0.50.

[0039] In order to lower the melting point of the solid electrolyte material, the molar ratio of O to Y can also be greater than 0.01 and 0.50 or less.

[0040] (The second solid electrolyte material)

[0041] The molar ratio A of O to Y in the surface region of the second solid electrolyte material can also be greater than the molar ratio B of O to Y in the whole of the second solid electrolyte material. Such a solid electrolyte material has a low melting point and high ionic conductivity. As an example, the value of the molar ratio A can also be greater than twice the value of the molar ratio B.

[0042] Herein, the surface region of the second solid electrolyte material refers to the region from the surface of the second solid electrolyte material to a depth of about 5 nm in the inward direction.

[0043] In order for the solid electrolyte material to have high ionic conductivity, the molar ratio A can also be 2.50 or less.

[0044] The X-ray diffraction pattern of the second solid electrolyte material can be measured using Cu-Kα rays. In the obtained X-ray diffraction pattern, peaks can also exist in the range of diffraction angles 2θ of 15.2° to 16.3°, 16.7° to 18.5°, 30.8° to 31.9°, 33.1° to 34.2°, 40.3° to 41.4°, 48.2° to 49.3°, and 53.1° to 54.2°. Such a solid electrolyte material has a low melting point and high ionic conductivity.

[0045] In order for the solid electrolyte material to have a low melting point and high ionic conductivity, the molar ratio of O to Y in the whole of the second solid electrolyte material can also be greater than 0.01 and 0.33 or less.

[0046] The shape of the solid electrolyte material of the first embodiment is not limited. Examples of the shape are needle-like, spherical, or ellipsoidal. The solid electrolyte material of the first embodiment can also be particles. The solid electrolyte material of the first embodiment can also be formed in a manner having a shape of a granule or a plate.

[0047] When the shape of the solid electrolyte material of the first embodiment is particulate (e.g., spherical), the solid electrolyte material of the first embodiment can also have a median particle size of 0.1 μm to 100 μm.

[0048] In order to improve the ionic conductivity of the solid electrolyte material of the first embodiment and to disperse the solid electrolyte material and the active material of the first embodiment well, the median particle size may also be 0.5 μm to 10 μm. The median particle size refers to the particle size when the cumulative volume in the particle size distribution based on volume is equal to 50%. The particle size distribution based on volume can be measured by a laser diffraction type measuring device or an image analysis device.

[0049] In order to disperse the solid electrolyte material and the active material of the first embodiment even better, the solid electrolyte material of the first embodiment may also have a median particle size smaller than that of the active material.

[0050] <Manufacturing method of solid electrolyte material>

[0051] The solid electrolyte material of the first embodiment can be manufactured by the following method.

[0052] First, as raw material powders, a plurality of halides are mixed.

[0053] As an example, in the case of producing a solid electrolyte material formed of Li, Y, Cl, and O, YCl 3 raw material powder and LiCl raw material powder are mixed. The obtained mixed powder is fired in an inert gas atmosphere (for example, an argon atmosphere having a dew point of -60°C or lower) in which the oxygen concentration and the moisture concentration are adjusted. The firing temperature can also be, for example, in the range of 200°C to 650°C. The obtained reaction product is left standing in an atmosphere having a relatively high dew point (for example, an argon atmosphere having a dew point of -30°C).

[0054] Next, the reaction product is fired, for example, in an inert gas atmosphere (for example, an argon atmosphere having a dew point of -60°C or lower) at a temperature above the melting point (for example, 550°C). By firing at a temperature above the melting point, O can exist throughout the material. Alternatively, as another example, the reaction product can also be fired in an inert gas atmosphere (for example, an argon atmosphere having a dew point of -60°C or lower) at a temperature below the melting point (for example, 400°C). By firing at a temperature below the melting point, the proportion of O in the surface region of the solid electrolyte material becomes larger.

[0055] In order to offset the compositional changes that may occur in the synthesis process, the raw material powders may be mixed in a pre-adjusted molar ratio. By selecting the raw material powders, the oxygen concentration in the atmosphere, the moisture concentration in the atmosphere, and the reaction time, the amount of oxygen in the solid electrolyte material is determined. By operating in this way, the solid electrolyte material of the first embodiment can be obtained.

[0056] The raw material powder can also be an oxide and a halide. For example, as the raw material powder, Y 2 O 3 、NH 4 Cl and LiCl can also be used.

[0057] It is considered that oxygen constituting the solid electrolyte material of the first embodiment is taken in from the atmosphere having a relatively high dew point described above.

[0058] (Second Embodiment)

[0059] Hereinafter, the second embodiment will be described. Matters described in the first embodiment may be omitted.

[0060] The battery of 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 of the positive electrode, the electrolyte layer, and the negative electrode contains the solid electrolyte material of the first embodiment. Since the battery of the second embodiment contains the solid electrolyte material of the first embodiment, it has excellent charge and discharge characteristics.

[0061] The solid electrolyte material having a low melting point is softer than the solid electrolyte material having a higher melting point. Therefore, the adhesion at the interface between solid electrolyte materials or at the interface between a solid electrolyte material and other materials (such as an active material) is improved. As a result, the battery resistance is reduced, and thus the charge and discharge characteristics of the battery are improved. Furthermore, even when the solid electrolyte material and other materials (such as an active material) are sintered, side reactions can be suppressed.

[0062] Figure 1 A cross-sectional view showing the battery 1000 of the second embodiment.

[0063] The battery 1000 includes a positive electrode 201, an electrolyte layer 202, and a negative electrode 203.

[0064] The positive electrode 201 contains positive electrode active material particles 204 and solid electrolyte particles 100.

[0065] The electrolyte layer 202 is disposed between the positive electrode 201 and the negative electrode 203.

[0066] The electrolyte layer 202 contains an electrolyte material (such as a solid electrolyte material).

[0067] The negative electrode 203 contains negative electrode active material particles 205 and solid electrolyte particles 100.

[0068] The solid electrolyte particles 100 are particles made of the solid electrolyte material of the first embodiment or particles containing the solid electrolyte material of the first embodiment as a main component. Herein, the "particles containing the solid electrolyte material of the first embodiment as a main component" refer to particles in which the most contained component is the solid electrolyte material of the first embodiment.

[0069] The positive electrode 201 contains a material capable of inserting and extracting metal ions (such as lithium ions). Such a material is, for example, a positive electrode active material (such as positive electrode active material particles 204).

[0070] Examples of the positive electrode active material are lithium-containing transition metal oxides, transition metal fluorides, polyanion materials, fluorinated polyanion materials, transition metal sulfides, transition metal fluorides, transition metal sulfur oxides, or transition metal nitrogen oxides. Examples of the lithium-containing transition metal oxides are LiNi 1-d-f Co d Al f O 2 (where 0 < d, 0 < f, and 0 < (d + f) < 1) or LiCoO 2 .

[0071] In the positive electrode 201, in order to disperse the positive electrode active material particles 204 and the solid electrolyte particles 100 well, the positive electrode active material particles 204 may also have a median particle size of 0.1 μm or more. Through such good dispersion, the charge-discharge characteristics of the battery 1000 are improved. In order to enable lithium to diffuse rapidly within the positive electrode active material particles 204, the positive electrode active material particles 204 may also have a median particle size of 100 μm or less. Due to the rapid diffusion of lithium, the battery 1000 can operate at a high output power. As described above, the positive electrode active material particles 204 may also have a median particle size of 0.1 μm to 100 μm.

[0072] In the positive electrode 201, in order to disperse the positive electrode active material particles 204 and the solid electrolyte particles 100 well, the positive electrode active material particles 204 may also have a larger median particle size than the solid electrolyte particles 100.

[0073] In order to improve the energy density and output power of the battery 1000, in the positive electrode 201, the ratio of the volume of the positive electrode active material particles 204 to the sum of the volumes of the positive electrode active material particles 204 and the solid electrolyte particles 100 may also be 0.30 to 0.95.

[0074] In order to improve the energy density and output power of the battery 1000, the positive electrode 201 may also have a thickness of 10 μm to 500 μm.

[0075] The electrolyte layer 202 contains an electrolyte material. The electrolyte material may also include the solid electrolyte material of the first embodiment. The electrolyte layer 202 may also be a solid electrolyte layer.

[0076] The electrolyte layer 202 may also be composed only of the solid electrolyte material of the first embodiment. Alternatively, the electrolyte layer 202 may also be composed only of a solid electrolyte material different from the solid electrolyte material of the first embodiment.

[0077] Examples of the solid electrolyte material different from the solid electrolyte material of the first embodiment are Li 2 MgX’ 4 、Li 2 FeX’ 4 、Li(Al, Ga, In)X’ 4 、Li 3 (Al, Ga, In)X’ 6 or LiI. Herein, X’ is at least one selected from F, Cl, Br, and I.

[0078] The electrolyte layer 202 not only contains the solid electrolyte material of the first embodiment, but may also contain a solid electrolyte material different from the solid electrolyte material of the first embodiment. The solid electrolyte material of the first embodiment and the solid electrolyte material different from the solid electrolyte material of the first embodiment may also be uniformly dispersed. The layer formed of the solid electrolyte material of the first embodiment and the layer formed of the solid electrolyte material different from the solid electrolyte material of the first embodiment may also be laminated along the lamination direction of the battery 1000.

[0079] In order to suppress a short circuit between the positive electrode 201 and the negative electrode 203 and improve the output power of the battery 1000, the electrolyte layer 202 may also have a thickness of 1 μm to 100 μm.

[0080] The negative electrode 203 contains a material capable of inserting and extracting metal ions (such as lithium ions). Such a material is, for example, a negative electrode active material (such as negative electrode active material particles 205).

[0081] Examples of the negative electrode active material are a metal material, a carbon material, an oxide, a nitride, a tin compound, or a silicon compound. The metal material may be a single metal or an alloy. Examples of the metal material are lithium metal or a lithium alloy. Examples of the carbon material are natural graphite, coke, carbon in the process of graphitization, carbon fiber, spherical carbon, artificial graphite, or amorphous carbon. From the viewpoint of capacity density, preferred examples of the negative electrode active material are silicon (i.e., Si), tin (i.e., Sn), a silicon compound, or a tin compound.

[0082] 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 also have a median particle size of 0.1 μm or more. Through this good dispersion, the charge and discharge characteristics of the battery are improved. In order to enable lithium to diffuse rapidly within the negative electrode active material particles 205, the negative electrode active material particles 205 may also have a median particle size of 100 μm or less. Due to the rapid diffusion of lithium, the battery can operate at a high output power. As described above, the negative electrode active material particles 205 may also have a median particle size of 0.1 μm to 100 μm.

[0083] 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 also have a median particle size larger than that of the solid electrolyte particles 100.

[0084] In order to improve the energy density and output power 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 also be 0.30 to 0.95.

[0085] In order to improve the energy density and output power of the battery 1000, the negative electrode 203 may also have a thickness of 10 μm to 500 μm.

[0086] In order to improve the ionic conductivity, chemical stability, and electrochemical stability, at least one of the positive electrode 201, the electrolyte layer 202, and the negative electrode 203 may also contain a solid electrolyte material different from the solid electrolyte material of the first embodiment.

[0087] Examples of this solid electrolyte material are halide solid electrolytes, sulfide solid electrolytes, oxide solid electrolytes, or organic polymer solid electrolytes.

[0088] Examples of halide solid electrolytes are Li 2 MgX’ 4 、Li 2 FeX’ 4 、Li(Al, Ga, In)X’ 4 、Li 3 (Al, Ga, In)X’ 6 or LiI. Among them, X’ is at least one selected from F, Cl, Br, and I.

[0089] Examples of sulfide solid electrolytes are Li 2 S-P 2 S 5 、Li 2 S-SiS 2 、Li2 SB 2 S 3 , Li 2 S-GeS 2 , Li 3.25 Ge 0.25 P 0.75 S 4 or Li 10 G 2 S 12 .

[0090] Examples of oxide solid electrolytes are:

[0091] (i)LiTi 2 (PO 4 ) 3 or NASICON type solid electrolytes such as its element substitution products,

[0092] (ii) (LaLi)TiO 3 Such perovskite solid electrolytes,

[0093] (iii)Li 14 ZnGe 4 O 16 , Li 4 SiO 4 、LiGeO 4 or LISICON type solid electrolytes such as its element substitution products,

[0094] (iv)Li 7 La 3 Zr 2 O 12 or a garnet-type solid electrolyte such as an element substitution body thereof, or

[0095] (v)Li 3 PO 4 or its N-substituted form.

[0096] Examples of organic polymer solid electrolytes are compounds of polymer compounds and lithium salts. The polymer compounds may also have an ethylene oxide structure. The polymer compounds having an ethylene oxide structure can contain a large amount of lithium salts, thereby further improving ion conductivity.

[0097] An example of a lithium salt is LiPF 6 , LiBF 4 、LiSbF 6 、LiAsF 6 、LiSO 3 CF 3 、LiN(SO 2 CF 3 )2 , LiN(SO 2 C 2 F 5 ) 2 , LiN(SO 2 CF 3 )(SO 2 C 4 F 9 ) or LiC(SO 2 CF 3 ) 3 . One lithium salt selected from them can also be used alone. Alternatively, a mixture of two or more lithium salts selected from them can also be used.

[0098] For the purpose of facilitating the transfer of lithium ions and improving the output power characteristics of the battery 1000, at least one 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.

[0099] The non-aqueous electrolyte contains a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent.

[0100] Examples of the non-aqueous solvent are a cyclic carbonate solvent, a chain carbonate solvent, a cyclic ether solvent, a chain ether solvent, a cyclic ester solvent, a chain ester solvent, or a fluorine solvent. Examples of the cyclic carbonate solvent are ethylene carbonate, propylene carbonate, or butylene carbonate. Examples of the chain carbonate solvent are dimethyl carbonate, ethyl methyl carbonate, or diethyl carbonate. Examples of the cyclic ether solvent are tetrahydrofuran, 1,4-dioxane, or 1,3-dioxolane. Examples of the chain ether solvent are 1,2-dimethoxyethane or 1,2-diethoxyethane. Examples of the cyclic ester solvent are γ-butyrolactone. Examples of the chain ester solvent are methyl acetate. Examples of the fluorine solvent are fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, ethyl methyl fluorocarbonate, or dimethyl fluorocarbonate.

[0101] One non-aqueous solvent selected from them can also be used alone. Alternatively, a mixture of two or more non-aqueous solvents selected from them can also be used.

[0102] Examples of the lithium salt are LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiSO 3 CF 3 , LiN(SO 2 CF 3 ) 2 , LiN(SO 2 C 2 F 5 ) 2, LiN(SO 2 CF 3 )(SO 2 C 4 F 9 ) or LiC(SO 2 CF 3 ) 3 . One lithium salt selected from them can also be used alone. Alternatively, a mixture of two or more lithium salts selected from them can also be used.

[0103] The concentration of the lithium salt is, for example, in the range of 0.5 mol / L to 2 mol / L.

[0104] As the gel electrolyte, a polymer material impregnated with a non-aqueous electrolyte can be used. Examples of the polymer material are polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, or a polymer having an ethylene oxide bond.

[0105] Examples of the cations contained in the ionic liquid are:

[0106] (i) aliphatic chain quaternary salts such as tetraalkylammonium or tetraalkylphosphonium,

[0107] (ii) aliphatic cyclic ammonium such as pyrrolidinium, morpholinium, imidazolinium, tetrahydropyrimidinium, piperazinium, or piperidinium, or

[0108] (iii) nitrogen-containing heterocyclic aromatic cations such as pyridinium or imidazolium.

[0109] Examples of the anions contained in the ionic liquid are PF 6 - , BF 4 - , SbF 6 - , AsF 6 - , SO 3 CF 3 - , N(SO 2 CF 3 ) 2 - , N(SO 2 C 2 F 5 ) 2 - , N(SO 2 CF 3 )(SO 2 C 4 F 9 ) - or C(SO 2 CF3 ) - 3。

[0110] The ionic liquid may also contain a lithium salt.

[0111] For the purpose of improving the adhesion between particles, at least one selected from the positive electrode 201, the electrolyte layer 202, and the negative electrode 203 may also contain a binder.

[0112] Examples of the binder are polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aromatic polyamide resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, methyl polyacrylate, ethyl polyacrylate, hexyl polyacrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropropylene, styrene-butadiene rubber, or carboxymethyl cellulose.

[0113] Copolymers can also be used as binders. Examples of such binders are copolymers of two or more materials selected from tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether, vinylidene fluoride, chlorotrifluoroethylene, ethylene, propylene, pentafluoropropylene, fluoromethyl vinyl ether, acrylic acid, and hexadiene. Mixtures of two or more selected from them can also be used as binders.

[0114] To improve the electron conductivity, at least one selected from the positive electrode 201 and the negative electrode 203 may also contain a conductive additive.

[0115] Examples of the conductive additive are:

[0116] (i) Graphite-based materials such as natural graphite or artificial graphite,

[0117] (ii) Carbon black-based materials such as acetylene black or Ketjen black,

[0118] (iii) Conductive fiber-based materials such as carbon fiber or metal fiber,

[0119] (iv) Carbon fluoride,

[0120] (v) Metal powder-based materials such as aluminum,

[0121] (vi) Conductive whisker-based materials such as zinc oxide or potassium titanate,

[0122] (vii) Conductive metal oxides such as titanium oxide, or

[0123] (viii) Conductive polymer compounds such as polyaniline, polypyrrole, or polythiophene.

[0124] For cost reduction, the conductive additives of (i) or (ii) above can also be used.

[0125] Examples of the shape of the battery according to the second embodiment include coin type, cylindrical type, square type, sheet type, button type, flat type, or laminated type.

[0126] The battery according to the second embodiment can also be manufactured, for example, by the following method: preparing materials for forming a positive electrode, materials for forming an electrolyte layer, and materials for forming a negative electrode, and producing a laminate in which a positive electrode, an electrolyte layer, and a negative electrode are sequentially arranged by a known method.

[0127] Examples

[0128] Hereinafter, the present disclosure will be described in more detail with reference to examples.

[0129] (Example 1)

[0130] [Production of solid electrolyte material]

[0131] In an argon atmosphere having a dew point of -60°C or lower and an oxygen concentration of 0.0001% by volume or lower (hereinafter referred to as "dry argon atmosphere"), as raw material powders, YCl 3 and LiCl were prepared such that the molar ratio of YCl 3 to LiCl became 1:3. These raw material powders were pulverized and mixed in a mortar. The obtained mixture was fired in an alumina crucible at 550°C for 1 hour and then pulverized in a mortar. The obtained reaction product was allowed to stand in an argon atmosphere having a dew point of -30°C and an oxygen concentration of 20.9% by volume for about 10 minutes. Further, it was fired in a dry argon atmosphere at 550°C for 1 hour and then pulverized in a mortar. By operating in this way, the solid electrolyte material of Example 1 was obtained.

[0132] [Composition analysis of solid electrolyte material]

[0133] The contents of Li and Y per unit weight of the solid electrolyte material of Example 1 were measured by high-frequency inductively coupled plasma optical emission spectrometry using a high-frequency inductively coupled plasma optical emission spectrometer (manufactured by Thermo Fisher Scientific, iCAP7400). The content of Cl in the solid electrolyte material of Example 1 was measured by ion chromatography using an ion chromatograph (manufactured by Dionex, ICS-2000). Based on the contents of Li, Y, and Cl obtained from these measurement results, the Li:Y:Cl molar ratio was calculated. As a result, the solid electrolyte material of Example 1 had an Li:Y:Cl molar ratio of 2.56:1.00:5.29.

[0134] The mass ratio of O to the entire solid electrolyte material in Example 1 was measured by the non-dispersive infrared absorption method using an oxygen, nitrogen, and hydrogen analyzer (manufactured by Horiba, Ltd., EMGA-930). As a result, the mass ratio of O was 0.22%. Based on this, the Y:O molar ratio was calculated. As a result, the solid electrolyte material of Example 1 had a Y:O molar ratio of 1.00:0.04.

[0135] In the compositional analysis, elements with a molar ratio of 0.001% or less relative to Y were regarded as impurities.

[0136] [Measurement of Melting Point]

[0137] In the measurement of the melting point, a thermal analysis device (manufactured by T.A. Instruments, Q1000) was used. In a nitrogen atmosphere, a solid electrolyte material of Example 1 (about 5 mg) was weighed and heated from 300 °C to 530 °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 made with the horizontal axis set as temperature and the vertical axis set as calorific value. Two points on the graph where the solid electrolyte material neither generated heat nor absorbed heat were connected by a straight line, and this was used as the baseline. Then, the intersection of the tangent line at the inflection point of the endothermic peak and the baseline was set as the melting point. As a result, the melting point of the solid electrolyte material of Example 1 was 500.6 °C. Figure 6 It is a graph showing the results of the thermal analysis of the solid electrolyte material of Example 1.

[0138] [X-ray Diffraction]

[0139] In the analysis of the crystal structure of the solid electrolyte material, an X-ray diffractometer (manufactured by Rigaku Corporation, MiniFlex600) was used. In a dry environment with a dew point of -45 °C or lower, the X-ray diffraction pattern of the solid electrolyte material of Example 1 was measured. As the X-ray source, Cu-Kα rays (wavelengths of and ) were used.

[0140] The results of the X-ray diffraction measurement showed that peaks were present at 15.83°, 18.03°, 31.37°, 33.72°, 40.85°, 48.74°, and 53.58°. Figure 2 It is a graph showing the X-ray diffraction pattern of the solid electrolyte material of Example 1.

[0141] [Evaluation of Ionic Conductivity]

[0142] Figure 3 It is a schematic diagram showing the compression molding die 300 used for evaluating the ionic conductivity of the solid electrolyte material.

[0143] The pressure forming die 300 includes an upper punch 301, a frame 302, and a lower punch 303. The frame 302 is formed of insulating polycarbonate. Both the upper punch 301 and the lower punch 303 are formed of electroconductive stainless steel.

[0144] Using Figure 3 the pressure forming die 300 shown in, the ionic conductivity of the solid electrolyte material of Example 1 was measured by the following method.

[0145] In a dry argon atmosphere, the powder 101 of the solid electrolyte material of Example 1 was filled inside the pressure forming die 300. Inside the pressure forming die 300, a pressure of 400 MPa was applied to the solid electrolyte material of Example 1 using the upper punch 301 and the lower punch 303.

[0146] In the state where the pressure is applied, the upper punch 301 and the lower punch 303 are connected to a potentiostat (Princeton Applied Research Corporation, Versa STAT4). The upper punch 301 is connected to a working electrode and a potential measuring terminal. The lower punch 303 is connected to a counter electrode and a reference electrode. The impedance of the solid electrolyte material of Example 1 was measured by electrochemical impedance spectroscopy at room temperature.

[0147] Figure 4 is a Cole - Cole plot showing the impedance measurement results of the solid electrolyte material of Example 1.

[0148] In Figure 4 the real value of the impedance at the measurement point where the absolute value of the phase of the complex impedance is the smallest is regarded as the resistance value of the solid electrolyte material for ionic conduction. Regarding this real value, refer to Figure 4 the arrow R shown in SE . Using this resistance value, based on the following mathematical formula (1), the ionic conductivity was calculated.

[0149] σ=(R SE ×S / t) -1 (1)

[0150] where σ is the ionic conductivity. S is the contact area of the solid electrolyte material with the upper punch 303 ( Figure 3 in, equal to the cross - sectional area of the hollow part of the frame 301). R SE is the resistance value of the solid electrolyte material in the impedance measurement. t is the thickness of the solid electrolyte material to which the pressure is applied ( Figure 3 in, equal to the thickness of the layer formed by the powder 101 of the solid electrolyte material).

[0151] The ionic conductivity of the solid electrolyte material of Example 1 measured at 25 °C was 2.4×10 -4 S / cm.

[0152] [Fabrication of Battery]

[0153] In a dry argon atmosphere, the solid electrolyte material of Example 1 and LiCoO as the active material were prepared in a volume ratio of 70:30. 2 These materials were mixed in an agate mortar. By operating like this, a mixture was obtained.

[0154] In an insulating cylinder with an inner diameter of 9.5 mm, 100 mg of the solid electrolyte material of Example 1, 10.0 mg of the above mixture, and 14.7 mg of aluminum powder were stacked in sequence. A pressure of 300 MPa was applied to this stack to form the first electrode and the solid electrolyte layer. The solid electrolyte layer had a thickness of 500 μm.

[0155] Next, a metal In foil was stacked on the solid electrolyte layer. The solid electrolyte layer was sandwiched between the metal In foil and the first 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 second electrode.

[0156] A current collector made of stainless steel was attached to the first electrode and the second electrode. Then, a current collecting lead was attached to this current collector. Finally, using an insulating collar, the inside of the insulating cylinder was blocked from the outside air atmosphere, and the inside of the cylinder was sealed. By operating like this, the battery of Example 1 was obtained.

[0157] [Charge-Discharge Test]

[0158] Figure 5 is a graph showing the initial discharge characteristics of the battery of Example 1. Figure 5 The results shown in were measured by the following method.

[0159] The battery of Example 1 was placed in a thermostat at 25 °C. At a current density of 86 μA / cm 2 , the battery of Example 1 was charged until a voltage of 3.7 V was reached. This current density corresponds to a 0.05 C rate. Next, at the same current density of 86 μA / cm 2 , the battery of Example 1 was discharged until a voltage of 1.9 V was reached.

[0160] As a result of the charge-discharge test, the battery of Example 1 had an initial discharge capacity of 536 μAh.

[0161] (Examples 2 and 3)

[0162] The solid electrolyte material of Example 2 was obtained by operating in the same manner as in Example 1, except that the time for allowing the reaction product to stand in an atmosphere having a dew point of -30°C was set to 30 minutes instead of about 10 minutes.

[0163] The solid electrolyte material of Example 3 was obtained by operating in the same manner as in Example 1, except that the time for allowing the reaction product to stand in an atmosphere having a dew point of -30°C was set to 9 hours instead of about 10 minutes.

[0164] The elemental ratios (molar ratios), melting points, oxygen contents, X-ray diffractions, and ionic conductivities of the solid electrolyte materials of Examples 2 and 3 were measured by operating in the same manner as in Example 1. The measurement results are shown in Tables 1 and 2. In addition, Figure 2 is a diagram showing the X-ray diffraction patterns of the solid electrolyte materials of Examples 2 and 3. Figure 6 is a diagram showing the results of thermal analysis of the solid electrolyte materials of Examples 2 and 3.

[0165] Using the solid electrolyte materials of Examples 2 and 3, the batteries of Examples 2 and 3 were obtained by operating in the same manner as in Example 1.

[0166] Using the batteries of Examples 2 and 3, charge-discharge tests were conducted by operating in the same manner as in Example 1. The batteries of Examples 2 and 3 were charged and discharged as well as the battery of Example 1.

[0167] (Comparative Example 1)

[0168] In a dry argon atmosphere, as raw material powders, YCl 3 and LiCl were prepared such that the molar ratio of YCl 3 to LiCl became 1:3. These raw material powders were pulverized and mixed in a mortar. The resulting mixture was fired in an alumina crucible at 550°C for 1 hour and then pulverized in a mortar. By operating in this manner, the solid electrolyte material of Comparative Example 1 was obtained.

[0169] The elemental ratios (molar ratios), melting points, oxygen contents, X-ray diffractions, and ionic conductivities of the solid electrolyte material of Comparative Example 1 were measured by operating in the same manner as in Example 1. The measurement results are shown in Tables 1 and 2. In addition, Figure 2 is a diagram showing the X-ray diffraction pattern of the solid electrolyte material of Comparative Example 1. Figure 6 is a diagram showing the results of thermal analysis of the solid electrolyte material of Comparative Example 1.

[0170] [Table 1]

[0171]

[0172] [Table 2]

[0173]

[0174] (Examination)

[0175] As shown in Table 1, the solid electrolyte materials of Examples 1 to 3 have a lower melting point compared to the solid electrolyte material of Comparative Example 1. Furthermore, the solid electrolyte materials of Examples 1 to 3 have a high ionic conductivity of 1×10 -5 S / cm or more near room temperature.

[0176] The batteries of Examples 1 to 3 were charged and discharged at 25°C.

[0177] Since the solid electrolyte materials of Examples 1 to 3 do not contain sulfur, hydrogen sulfide is not generated.

[0178] (Example 4)

[0179] [Production of Solid Electrolyte Material]

[0180] In a dry argon atmosphere, as raw material powders, YCl 3 and LiCl were prepared such that the molar ratio of YCl 3 to LiCl became 1:3. These raw material powders were pulverized and mixed in a mortar. The obtained mixture was fired in an alumina crucible at 550°C for 1 hour and then pulverized in a mortar. The obtained reaction product was allowed to stand in an argon atmosphere having a dew point of -30°C and an oxygen concentration of 20.9 vol% for about 10 minutes. Furthermore, it was fired in a dry argon atmosphere at 400°C for 1 hour and then pulverized in a mortar. By operating in this way, the solid electrolyte material of Example 4 was obtained.

[0181] [Composition Analysis of Solid Electrolyte Material]

[0182] Operating in the same manner as in Example 1, the contents of Li, Y, and Cl in the entire solid electrolyte material of Example 4 were measured, and the Li:Y:Cl molar ratio was calculated. As a result, the solid electrolyte material of Example 4 has an Li:Y:Cl molar ratio of 2.56:1.00:5.16.

[0183] Operating in the same manner as in Example 1, the mass ratio of O to the entire solid electrolyte material of Example 4 was measured. As a result, the mass ratio of O is 0.29%. Based on this, the Y:O molar ratio was calculated. As a result, the solid electrolyte material of Example 4 has a Y:O molar ratio of 1.00:0.06.

[0184] The molar ratio of O to Y in the surface region of the solid electrolyte material of Example 4 is measured by X-ray photoelectron spectroscopy using a scanning X-ray photoelectron spectrometer (ULVAC-PHI, Inc., PHI Quantera SXM). The X-ray source uses Al-Kα rays. As a result, the solid electrolyte material of Example 4 has a Y:O molar ratio of 1.00:0.15 in the surface region. The surface region in the present disclosure refers to the region measured by such an operation. The thickness of the surface region of the solid electrolyte material of Example 4 is about 5 nm from the surface of the solid electrolyte material to the inside.

[0185] In the composition analysis, elements having a molar ratio of 0.001% or less relative to Y are regarded as impurities.

[0186] [Determination of melting point]

[0187] The melting point of the solid electrolyte material of Example 4 was measured in the same manner as in Example 1. As a result, the melting point of the solid electrolyte material of Example 4 was 498.8°C. Figure 10 This is a diagram showing the results of thermal analysis of the solid electrolyte material of Example 4.

[0188] [X-ray diffraction]

[0189] In the same manner as in Example 1, the X-ray diffraction pattern of the solid electrolyte material of Example 4 was measured.

[0190] As a result of X-ray diffraction measurement, peaks were present at 15.79°, 17.99°, 31.33°, 33.67°, 40.84°, 48.74°, and 53.56°. Figure 7 This is a diagram showing an X-ray diffraction pattern of the solid electrolyte material of Example 4.

[0191] [Charge and discharge test]

[0192] The solid electrolyte material of Example 4 was used in the same manner as in Example 1 to obtain a battery of Example 4.

[0193] Figure 9 This is a graph showing the initial discharge characteristics of the battery of Example 4. Figure 9 The results shown in were determined by the following method.

[0194] The battery of Example 4 was placed in a thermostatic chamber at 25°C. 2 The battery of Example 7 was charged at a current density of 83 μA / cm2 until the voltage reached 3.7 V. This current density is equivalent to a 0.05C rate. 2The current density discharges the battery of Example 4 until the voltage reaches 1.9 V.

[0195] As a result of the charge-discharge test, the battery of Example 4 had an initial discharge capacity of 642 μAh.

[0196] (Examples 5 and 6)

[0197] The solid electrolyte material of Example 5 was obtained by operating in the same manner as in Example 4, except that the time for allowing the reaction product to stand in an atmosphere having a dew point of -30 °C was set to 30 minutes instead of about 10 minutes.

[0198] The solid electrolyte material of Example 6 was obtained by operating in the same manner as in Example 4, except that the time for allowing the reaction product to stand in an atmosphere having a dew point of -30 °C was set to 2 hours instead of about 10 minutes.

[0199] Operating in the same manner as in Example 4, the elemental ratios (molar ratios), melting points, oxygen contents, X-ray diffractions, and ionic conductivities of the solid electrolyte materials of Examples 5 and 6 were measured. The measurement results are shown in Tables 3 and 4. In addition, Figure 7 is a diagram showing the X-ray diffraction patterns of the solid electrolyte materials of Examples 5 and 6. Figure 10 is a diagram showing the results of the thermal analysis of the solid electrolyte materials of Examples 5 and 6.

[0200] Using the solid electrolyte materials of Examples 5 and 6, the batteries of Examples 5 and 6 were obtained by operating in the same manner as in Example 1.

[0201] Using the batteries of Examples 5 and 6, a charge-discharge test was performed in the same manner as in Example 4. The batteries of Examples 5 and 6 were charged and discharged as well as the battery of Example 4.

[0202] (Comparative Example 2)

[0203] The solid electrolyte material of Comparative Example 2 was obtained by operating in the same manner as in Example 7, except that the time for allowing the reaction product to stand in an atmosphere having a dew point of -30 °C was set to 9 hours instead of about 10 minutes.

[0204] Operating in the same manner as in Example 7, the elemental ratios (molar ratios), melting points, oxygen contents, X-ray diffractions, and ionic conductivities of the solid electrolyte materials of Comparative Examples 1 and 2 were measured. The measurement results are shown in Tables 3 and 4. In addition, Figure 7 is a diagram showing the X-ray diffraction patterns of the solid electrolyte materials of Comparative Examples 1 and 2. Figure 10 is a diagram showing the results of the thermal analysis of the solid electrolyte materials of Comparative Examples 1 and 2.

[0205] Using the solid electrolyte material of Comparative Example 2, operating in the same manner as in Example 4, a battery of Comparative Example 2 was obtained.

[0206] Using the battery of Comparative Example 2, operating in the same manner as in Example 4, a charge-discharge test was conducted, but the initial discharge capacity was 1 mAh or less. The battery of Comparative Example 2 was neither charged nor discharged.

[0207] [Table 3]

[0208]

[0209] [Table 4]

[0210]

[0211] (Examination)

[0212] As shown in Table 3, the solid electrolyte materials of Examples 4 to 6 have a lower melting point compared to the solid electrolyte material of Comparative Example 1. Furthermore, the solid electrolyte materials of Examples 4 to 6 have a high ionic conductivity of 1×10 -5 S / cm or more near room temperature. On the other hand, the solid electrolyte material of Comparative Example 2 has an ionic conductivity of less than 1×10 -5 S / cm.

[0213] As shown in Table 3, if the molar ratio of O to Y in the whole of the solid electrolyte material is greater than 0.01 and 0.33 or less, the solid electrolyte material has a low melting point and a high ionic conductivity.

[0214] The batteries of Examples 4 to 6 were charged and discharged at 25°C.

[0215] Since the solid electrolyte materials of Examples 4 to 6 do not contain sulfur, hydrogen sulfide is not generated.

[0216] As described above, the solid electrolyte material of the present disclosure is suitable because it provides a battery having a low melting point and a high lithium ion conductivity and capable of being charged and discharged well.

[0217] Industrial Applicability

[0218] The solid electrolyte material of the present disclosure is used, for example, in all-solid-state lithium ion secondary batteries.

[0219] Explanation of Symbols

[0220] 100 Solid electrolyte particles

[0221] 101 Powder of solid electrolyte material

[0222] 201 Positive electrode

[0223] 202 electrolyte layer

[0224] 203 negative electrode

[0225] 204 positive electrode active material particles

[0226] 205 negative electrode active material particles

[0227] 300 compression molding die

[0228] 301 upper part of punch

[0229] 302 frame type

[0230] 303 lower part of punch

[0231] 1000 battery

Claims

1. A solid electrolyte material comprising Li, Y, X and O, wherein, X is one selected from F, Cl, Br and I, and the molar ratio of O to Y is greater than 0.01 and less than 0.52, the molar ratio of Li to Y is 2.2 to 2.56, and the molar ratio of X to Y is 3.5 to 5.

9.

2. The solid electrolyte material according to claim 1, wherein, X is Cl.

3. The solid electrolyte material according to claim 1 or 2, further comprising at least one selected from Mg, Ca, Zn, Sr, Ba, Al, Sc, Ga, Bi, La, Zr, Hf, Ta and Nb.

4. The solid electrolyte material according to claim 1 or 2, wherein, in the X-ray diffraction pattern obtained by X-ray diffraction measurement using Cu-Kα, peaks exist in the range of diffraction angle 2θ of 15.2° to 16.4°, 16.7° to 18.6°, 30.8° to 31.9°, 33.2° to 34.3°, 40.3° to 41.4°, 48.2° to 49.3° and 53.0° to 54.2°.

5. The solid electrolyte material according to claim 1 or 2, wherein, the molar ratio of O to Y is greater than 0.01 and 0.50 or less.

6. The solid electrolyte material according to claim 1 or 2, wherein, the molar ratio of O to Y in the surface region of the solid electrolyte material is greater than the molar ratio of O to Y in the whole of the solid electrolyte material.

7. The solid electrolyte material according to claim 1 or 2, wherein, in the X-ray diffraction pattern obtained by X-ray diffraction measurement using Cu-Kα, peaks exist in the range of diffraction angle 2θ of 15.2° to 16.3°, 16.7° to 18.5°, 30.8° to 31.9°, 33.1° to 34.2°, 40.3° to 41.4°, 48.2° to 49.3° and 53.1° to 54.2°.

8. The solid electrolyte material according to claim 1 or 2, wherein, the molar ratio of O to Y in the whole of the solid electrolyte material is greater than 0.01 and 0.33 or less.

9. A battery comprising: a positive electrode; a negative electrode; and an electrolyte layer disposed between the positive electrode and the negative electrode, wherein, at least one selected from the positive electrode, the negative electrode and the electrolyte layer contains the solid electrolyte material according to any one of claims 1 to 8.

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