Solid electrolyte material and battery using the same

Abstract

This solid electrolyte material contains Li, Sc, and Cl. In an X-ray diffraction pattern of the solid electrolyte material obtained using Cu-Kα rays, at least two peaks are resent in the range of a diffraction angle 2θ that is 27-36° (inclusive), and the half-width of the peak having the highest intensity within the range of the diffraction angle 2θ that is 27-36° (inclusive) is 0.5°or less.

Description

[Technical Field]

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

[0002] Patent Document 1 describes a compound having the composition formula Li 6-3δ Y 1+δ-α M α Cl 6-x-y Br x I y (M is at least one element selected from the group consisting of Al, Sc, Ga, and Bi, and -1<δ<1, 0<α<2, 0<1+δ-a, 0≦x≦6, 0≦y≦6, and x+y≦6 are satisfied). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 135320 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide a solid electrolyte material having high lithium ion conductivity. [Means for solving the problem]

[0005] The solid electrolyte material of the present disclosure contains Li, Sc, and Cl, and in an X-ray diffraction pattern of the solid electrolyte material obtained using Cu-Kα radiation, at least two peaks are present in a diffraction angle 2θ range of 27° or more and 36° or less, and the half-width of the peak having the greatest intensity in the diffraction angle 2θ range of 27° or more and 36° or less is 0.5° or less. [Effects of the Invention]

[0006] The present disclosure provides a solid electrolyte material with high lithium ion conductivity. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 shows a cross-sectional view of a battery 1000 according to a second embodiment. [Figure 2] FIG. 2 shows a schematic diagram of a pressing die 300 used to evaluate the ionic conductivity of a solid electrolyte material. [Figure 3] FIG. 3 is a graph showing a Cole-Cole plot obtained by measuring the impedance of the solid electrolyte material according to Example 1. [Figure 4] FIG. 4 is a graph showing the X-ray diffraction patterns of the solid electrolyte materials according to Examples 1 to 12 and Comparative Examples 1 to 3. [Figure 5] FIG. 5 is a graph showing the initial discharge characteristics of the battery according to 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, Sc, and Cl, In the X-ray diffraction pattern of the solid electrolyte material obtained using Cu-Kα radiation, At least two peaks are present in the diffraction angle 2θ range of 27° to 36°, The half-width of the peak having the greatest intensity within the diffraction angle 2θ range of 27° to 36° is 0.5° or less.

[0010] The solid electrolyte material according to the first embodiment has high lithium ion conductivity.

[0011] Here, high lithium ion conductivity is, for example, 4.4 × 10 -4That is, the solid electrolyte material according to the first embodiment has a specific resistance of, for example, 4.4×10 -4 It may have an ionic conductivity of 5 S / cm or more.

[0012] 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).

[0013] The half-width means the distance between two points having an intensity that is half the maximum value of the peak. In the X-ray diffraction pattern of the solid electrolyte material according to the first embodiment, the half width of the peak having the largest intensity within a diffraction angle 2θ range of 27° to 36° may be greater than 0° and less than 0.5°. The half width may be greater than 0° and less than 0.42°. The upper and lower limits of the half width can be defined by any combination selected from the following numerical values: 0.15, 0.16, 0.17, 0.18, 0.19, 0.21, 0.22, 0.25, and 0.5.

[0014] The solid electrolyte material according to the first embodiment may have an X-ray diffraction pattern obtained using Cu-Kα radiation in which at least one peak is present in a diffraction angle 2θ range of 13° to 18° and at least one peak is present in a diffraction angle 2θ range of 45° to 52°. The half-width of the peak having the greatest intensity within the diffraction angle 2θ range of 13° to 18° may be 0.5° or less.

[0015] The solid electrolyte material according to the first embodiment can be used to obtain a battery with excellent charge / discharge characteristics. An example of such a battery is an all-solid-state battery. The all-solid-state battery may be a primary battery or a secondary battery.

[0016] The solid electrolyte material according to the first embodiment desirably contains substantially no sulfur. The fact that the solid electrolyte material according to the first embodiment is substantially free of sulfur means that the solid electrolyte material does not contain sulfur as a constituent element, except for sulfur that is 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. The solid electrolyte material according to the first embodiment preferably does not contain sulfur. A sulfur-free solid electrolyte material does not generate hydrogen sulfide even when exposed to the atmosphere, and is therefore highly safe. The sulfide solid electrolyte disclosed in Patent Document 1 may generate hydrogen sulfide when exposed to the atmosphere.

[0017] The solid electrolyte material according to the first embodiment may consist essentially of Li, Sc, and Cl. Here, "the solid electrolyte material according to the first embodiment consists essentially of Li, Sc, and Cl" means that the molar ratio (i.e., molar fraction) of the total amount of substance of Li, Sc, and Cl to the total amount of substance of all elements constituting the solid electrolyte material according to the first embodiment is 90% or more. As an example, the molar ratio may be 95% or more. The solid electrolyte material according to the first embodiment may consist only of Li, Sc, and Cl.

[0018] The solid electrolyte material according to the first embodiment may contain Y. The solid electrolyte material according to the first embodiment may consist essentially of Li, Y, Sc, and Cl. Here, "the solid electrolyte material according to the first embodiment consists essentially of Li, Y, Sc, and Cl" means that the molar ratio (i.e., molar fraction) of the total amount of substance of Li, Y, Sc, and Cl to the total amount of substance of all elements constituting the solid electrolyte material according to the first embodiment is 90% or more. As an example, the molar ratio may be 95% or more. The solid electrolyte material according to the first embodiment may consist only of Li, Y, Sc, and Cl.

[0019] The solid electrolyte material according to the first embodiment may be a material represented by the following composition formula (1). Li 6-3b(Y 1-a Sc a ) b Cl6···(1) Here, the following two formulas: 0.3≦a≦1, and 0.7≦b≦1.2 is satisfied.

[0020] The material represented by composition formula (1) has high ionic conductivity.

[0021] In order to increase the ionic conductivity of the solid electrolyte material, the formula (1) may satisfy the formula: 0.35≦a≦1. In order to further increase the ionic conductivity of the solid electrolyte material, the formula: 0.7≦a≦1 may be satisfied.

[0022] In order to enhance the ionic conductivity of the solid electrolyte material, the formula: 0.9≦b≦1.2 may be satisfied in the composition formula (1).

[0023] 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, for example, a particle shape. The solid electrolyte material according to the first embodiment may be formed into a pellet or plate shape.

[0024] When the solid electrolyte material according to the first embodiment has a particulate (e.g., spherical) shape, the solid electrolyte material may have a median diameter of 0.1 μm or more and 100 μm or less. The median diameter refers to the particle size at which the cumulative volume in the volume-based particle size distribution is 50%. The volume-based particle size distribution is measured, for example, by a laser diffraction measurement device or an image analysis device.

[0025] The solid electrolyte material according to the first embodiment may have a median diameter of 0.5 μm or more and 10 μm or less. This allows the solid electrolyte material according to the first embodiment to have higher ionic conductivity. Furthermore, the solid electrolyte material according to the first embodiment and other materials such as active materials can be dispersed well.

[0026] The solid electrolyte material according to the first embodiment is produced, for example, by the following method.

[0027] Raw material powders are prepared and mixed to obtain a desired composition. The raw material powders may be, for example, halides.

[0028] As an example, if the desired composition is Li3Y 0.7 Sc 0.3 In the case of Cl6, LiCl raw material powder, YCl3 raw material powder, and ScCl3 raw material powder are mixed to obtain a LiCl:YCl3:ScCl3 molar ratio of approximately 3:0.7:0.3. The raw material powders may be mixed in a pre-adjusted molar ratio to offset compositional changes that may occur during the synthesis process.

[0029] The mixture of raw material powders is fired in an inert gas atmosphere or in a vacuum to obtain a reactant. Alternatively, the mixture of raw material powders may be reacted with each other mechanochemically, i.e., using a mechanochemical milling method, in a mixing device such as a planetary ball mill to obtain a reactant, and the resulting reactant may be fired in an inert gas atmosphere or in a vacuum. The inert gas atmosphere is, for example, an argon atmosphere or a nitrogen atmosphere.

[0030] By these methods, the solid electrolyte material according to the first embodiment can be obtained.

[0031] (Second embodiment) The second embodiment will be described below. The matters described in the first embodiment may be omitted as appropriate.

[0032] In the second embodiment, an electrochemical device will be described that uses the solid electrolyte material according to the first embodiment. As an example of the electrochemical device according to the second embodiment, a battery will be described below.

[0033] The battery according to the second embodiment includes a positive electrode, an electrolyte layer, and a negative electrode. The electrolyte layer is provided 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. The battery according to the second embodiment has excellent charge / discharge characteristics because it contains the solid electrolyte material according to the first embodiment.

[0034] The battery according to the second embodiment may be an all-solid-state battery.

[0035] FIG. 1 shows a cross-sectional view of a battery 1000 according to a second embodiment.

[0036] The battery 1000 includes a positive electrode 201, an electrolyte layer 202, and a negative electrode 203. The electrolyte layer 202 is provided between the positive electrode 201 and the negative electrode 203.

[0037] The positive electrode 201 contains positive electrode active material particles 204 and solid electrolyte particles 100 .

[0038] The electrolyte layer 202 contains an electrolyte material, such as a solid electrolyte material.

[0039] The negative electrode 203 contains negative electrode active material particles 205 and solid electrolyte particles 100 .

[0040] The solid electrolyte particles 100 are 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. Particles containing the solid electrolyte material according to the first embodiment as a main component refer to particles in which the solid electrolyte material according to the first embodiment is the component contained most abundantly by mass. The solid electrolyte particles 100 may be particles made of the solid electrolyte material according to the first embodiment.

[0041] The positive electrode 201 contains a material capable of absorbing and releasing metal ions such as lithium ions. The material is, for example, a positive electrode active material (for example, positive electrode active material particles 204).

[0042] Examples of the positive electrode active material include lithium-containing transition metal oxides, transition metal fluorides, polyanionic materials, fluorinated polyanionic materials, transition metal sulfides, transition metal oxyfluorides, transition metal oxysulfides, and transition metal oxynitrides. Examples of lithium-containing transition metal oxides include Li(Ni,Co,Mn)O2, Li(Ni,Co,Al)O2, and LiCoO2.

[0043] In the present disclosure, "(A,B,C)" means "at least one selected from the group consisting of A, B, and C."

[0044] The positive electrode active material particles 204 may have a median diameter of 0.1 μm or more and 100 μm or less. When the positive electrode active material particles 204 have a median diameter of 0.1 μm or more, the positive electrode active material particles 204 and the solid electrolyte particles 100 can be well dispersed in the positive electrode 201. This improves the charge / discharge characteristics of the battery. When the positive electrode active material particles 204 have a median diameter of 100 μm or less, the lithium diffusion rate within the positive electrode active material particles 204 improves. This allows the battery to operate at high power.

[0045] The positive electrode active material particles 204 may have a larger median diameter than the solid electrolyte particles 100. This allows the positive electrode active material particles 204 and the solid electrolyte particles 100 to be dispersed well.

[0046] To increase the energy density and output of the battery, 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.

[0047] To increase the energy density and output of the battery, the positive electrode 201 may have a thickness of 10 μm or more and 500 μm or less.

[0048] The electrolyte layer 202 contains an electrolyte material. The electrolyte material is, for example, a solid electrolyte material. The electrolyte layer 202 may be a solid electrolyte layer.

[0049] The electrolyte layer 202 may contain the solid electrolyte material according to the first embodiment. The electrolyte layer 202 may be made of only the solid electrolyte material according to the first embodiment. Alternatively, the electrolyte layer 202 may be made of only a solid electrolyte material different from the solid electrolyte material according to the first embodiment.

[0050] 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 element selected from the group consisting of F, Cl, Br, and I.

[0051] 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.

[0052] 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 in the electrolyte layer 202. 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.

[0053] The electrolyte layer 202 may have a thickness of 1 μm or more and 1000 μm or less. When the electrolyte layer 202 has a thickness of 1 μm or more, the positive electrode 201 and the negative electrode 203 are less likely to short-circuit. When the electrolyte layer 202 has a thickness of 1000 μm or less, the battery can operate at high power.

[0054] The negative electrode 203 contains a material capable of absorbing and releasing metal ions such as lithium ions. The material is, for example, a negative electrode active material (for example, negative electrode active material particles 205).

[0055] 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 single 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 (Si), tin (Sn), a silicon compound, or a tin compound.

[0056] The negative electrode active material particles 205 may have a median diameter of 0.1 μm or more and 100 μm or less. When the negative electrode active material particles 205 have a median diameter of 0.1 μm or more, the negative electrode active material particles 205 and the solid electrolyte particles 100 can be well dispersed in the negative electrode 203. This improves the charge / discharge characteristics of the battery. When the negative electrode active material particles 205 have a median diameter of 100 μm or less, the lithium diffusion rate within the negative electrode active material particles 205 improves. This allows the battery to operate at high power.

[0057] The negative electrode active material particles 205 may have a larger median diameter than the solid electrolyte particles 100. This allows the negative electrode active material particles 205 and the solid electrolyte particles 100 to be dispersed well.

[0058] In order to increase the energy density and output of the battery, 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.

[0059] To increase the energy density and output of the battery, the negative electrode 203 may have a thickness of 10 μm or more and 500 μm or less.

[0060] 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 for the purpose of increasing ionic conductivity, chemical stability, and electrochemical stability.

[0061] As mentioned above, the second solid electrolyte material may be a halide solid electrolyte.

[0062] 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 element selected from the group consisting of F, Cl, Br, and I.

[0063] Other examples of halide solid electrolytes are Li p Me q Y r Z6, where p + m'q + 3r = 6 and r > 0. Me is at least one element selected from the group consisting of metal elements and metalloid elements other than Li and Y. Z is at least one element selected from the group consisting of F, Cl, Br, and I. The value of m' represents the valence of Me. "Metalloid elements" are B, Si, Ge, As, Sb, and Te. "Metal elements" are all elements in Groups 1 to 12 of the Periodic Table (excluding hydrogen) and all elements in Groups 13 to 16 of the Periodic Table (excluding B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se). To increase the ionic conductivity of the halide solid electrolyte, Me may be at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Zn, Sc, Al, Ga, Bi, Zr, Hf, Ti, Sn, Ta, and Nb.

[0064] The second solid electrolyte material may be a sulfide solid electrolyte.

[0065] 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.

[0066] The second solid electrolyte material may be an oxide solid electrolyte.

[0067] 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.

[0068] The second solid electrolyte material may be an organic polymer solid electrolyte.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] The nonaqueous electrolyte contains a nonaqueous solvent and a lithium salt dissolved in the nonaqueous solvent. Examples of the nonaqueous solvent include a cyclic carbonate ester solvent, a chain carbonate ester 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 ester solvent are ethylene carbonate, propylene carbonate, or butylene carbonate. Examples of the chain carbonate ester 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. An example of the cyclic ester solvent is γ-butyrolactone. An example of the chain ester solvent is methyl acetate. Examples of fluorine-containing solvents include fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethyl methyl carbonate, and fluorodimethylene carbonate. One non-aqueous solvent selected from these may be used alone. Alternatively, a mixture of two or more non-aqueous solvents selected from these may be used.

[0073] Examples of lithium salts are LiPF6, LiBF4, LiSbF6, LiAsF6, LiSO3CF3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiN(SO2CF3)(SO2C4F9), or LiC(SO2CF3)3. 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. The concentration of the lithium salt is, for example, 0.5 mol / L or more and 2 mol / L or less.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] The ionic liquid may contain a lithium salt.

[0078] 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.

[0079] 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 of the above materials may also be used as binders.

[0080] At least one selected from the group consisting of the positive electrode 201 and the negative electrode 203 may contain a conductive additive for the purpose of increasing electronic conductivity.

[0081] 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 To reduce costs, the above-mentioned conductive additive (i) or (ii) may be used.

[0082] 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. [Example]

[0083] (Example) Hereinafter, the present disclosure will be described in more detail with reference to examples and comparative examples.

[0084] Example 1 (Preparation of solid electrolyte materials) In an argon atmosphere having a dew point of -60°C or less (hereinafter referred to as "dry argon atmosphere"), raw material powders of LiCl, YCl3, and ScCl3 were prepared in a molar ratio of LiCl:YCl3:ScCl3 = 3:0.7:0.3. These raw materials were ground and mixed in a mortar. The resulting mixture was placed in an alumina crucible and fired at 600°C for 60 minutes in a dry argon atmosphere. The resulting fired product was ground in an agate mortar. In this way, a solid electrolyte material according to Example 1 was obtained. The solid electrolyte material according to Example 1 was composed of Li3Y 0.7 Sc 0.3 It had a composition represented by Cl6.

[0085] The Li, Y, and Sc contents of the solid electrolyte material according to Example 1 were measured by inductively coupled plasma atomic emission spectroscopy using a high-frequency inductively coupled plasma optical emission spectrometer (iCAP7400, manufactured by Thermo Fisher Scientific). Based on the Li, Y, and Sc contents obtained from these measurement results, the Li:Y:Sc molar ratio was calculated. As a result, the solid electrolyte material according to Example 1 had a Li:Y:Sc molar ratio of 3:0.7:0.3, which was the same as the molar ratio of the raw material powder.

[0086] (Evaluation of ionic conductivity) FIG. 2 is a schematic diagram showing a pressure forming die 300 used to evaluate the ionic conductivity of the solid electrolyte material.

[0087] The pressure molding die 300 had an upper punch 301, a frame 302, and a lower punch 303. The upper punch 301 and the lower punch 303 were both made of electronically conductive stainless steel. The frame 302 was made of insulating polycarbonate.

[0088] The ionic conductivity of the solid electrolyte material of Example 1 was measured by the following method using the pressure molding die 300 shown in FIG.

[0089] In a dry atmosphere having a dew point of −30° C. or less, the powder of the solid electrolyte material according to Example 1 (i.e., the powder of the solid electrolyte material 101 in FIG. 2 ) was filled into the inside of a pressure molding die 300. Inside the pressure molding die 300, a pressure of 300 MPa was applied to the solid electrolyte material according to Example 1 using an upper punch 301 and a lower punch 303.

[0090] While the pressure was still applied, the upper punch 301 and the lower punch 303 were connected to a potentiostat (VersaSTAT4, manufactured by Princeton Applied Research) equipped with a frequency response analyzer. The upper punch 301 was connected to a working electrode and a potential measurement terminal. The lower punch 303 was connected to a counter electrode and a reference electrode. The impedance of the solid electrolyte material according to Example 1 was measured at room temperature by electrochemical impedance measurement.

[0091] FIG. 3 is a graph showing a Cole-Cole plot obtained by measuring the impedance of the solid electrolyte material according to Example 1.

[0092] 3, 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 RSE Using the resistance value, the ionic conductivity was calculated based on the following formula (2). σ=(R SE ×S / t) -1 ···(2) Here, σ represents ionic conductivity, S represents 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. 2), and R SE represents the resistance value of the solid electrolyte material in impedance measurement, and t represents the thickness of the solid electrolyte material (i.e., the thickness of the layer formed from the powder 101 of the solid electrolyte material in FIG. 2).

[0093] The ionic conductivity of the solid electrolyte material according to Example 1 measured at 22°C was 4.4 × 10 -4 It was S / cm.

[0094] (X-ray diffraction measurement) 4 is a graph showing the X-ray diffraction pattern of the solid electrolyte material according to Example 1. The X-ray diffraction pattern was measured as follows.

[0095] The X-ray diffraction pattern of the solid electrolyte material of Example 1 was measured using an X-ray diffractometer (MiniFlex600, manufactured by RIGAKU) in a dry atmosphere with a dew point of -50°C or less. Cu-Kα radiation (wavelengths 1.5405 Å and 1.5444 Å) was used as the X-ray source. The X-ray diffraction pattern was measured by the θ-2θ method.

[0096] In the obtained X-ray diffraction pattern, the half-width of the peak having the greatest intensity within the diffraction angle 2θ range of 27° to 36° was measured, and the result was that the half-width was 0.21°.

[0097] (Battery construction) In a dry argon atmosphere, the solid electrolyte material according to Example 1 and the active material LiCoO2 were prepared in a volume ratio of 30:70. These materials were mixed in an agate mortar. In this way, a positive electrode mixture was obtained.

[0098] In an insulating tube, the solid electrolyte material (100 mg) according to Example 1, the positive electrode mixture (10 mg), and aluminum powder (14.7 mg) were stacked in this order. A pressure of 300 MPa was applied to the resulting stack to form an electrolyte layer and a first electrode. The electrolyte layer had a thickness of 500 μm.

[0099] Next, metal In (thickness: 200 μm) was laminated on the electrolyte layer. A pressure of 80 MPa was applied to this laminate to form a second electrode. The first electrode was a positive electrode, and the second electrode was a negative electrode.

[0100] Next, current collectors made of stainless steel were placed on the first electrode and the second electrode, and current collecting leads were attached to the current collectors.

[0101] Finally, the inside of the insulating cylinder was isolated from the outside atmosphere using an insulating ferrule, and the inside of the cylinder was sealed. In this way, the battery according to Example 1 was obtained.

[0102] (Charge / discharge test) 5 is a graph showing the initial discharge characteristics of the battery according to Example 1. A charge / discharge test was carried out as follows.

[0103] The battery according to Example 1 was placed in a thermostatic chamber maintained at 25°C.

[0104] The battery according to Example 1 was charged at a current value corresponding to a 0.05C rate (20-hour rate) relative to the theoretical capacity of the battery until the voltage reached 3.7V.

[0105] Next, the battery according to Example 1 was discharged at a current value corresponding to a 0.05C rate until the voltage reached 1.9V.

[0106] As a result of the charge-discharge test, the battery according to Example 1 had an initial discharge capacity of 0.51 mAh.

[0107] <Examples 2 to 12> (Preparation of solid electrolyte materials) In Examples 2 to 12, LiCl, YCl, and ScCl were prepared as raw material powders in a molar ratio of LiCl:YCl:ScCl = (6-3b):(1-a)b:ab. Except for the above, the solid electrolyte materials of Examples 2 to 12 were obtained in the same manner as in Example 1. The values ​​of a and b are shown in Table 1.

[0108] (Evaluation of ionic conductivity) The ionic conductivities of the solid electrolyte materials according to Examples 2 to 12 were measured in the same manner as in Example 1. The measurement results are shown in Table 1.

[0109] (X-ray diffraction measurement) The X-ray diffraction patterns of the solid electrolyte materials according to Examples 2 to 12 were measured in the same manner as in Example 1. Fig. 4 is a graph showing the X-ray diffraction patterns of the solid electrolyte materials according to Examples 2 to 12. The position and half-width of the peak having the largest intensity within the diffraction angle 2θ range of 27° or more and 36° or less are shown in Table 1.

[0110] (Charge / discharge test) Batteries according to Examples 2 to 12 were obtained in the same manner as in Example 1 using the solid electrolyte materials according to Examples 2 to 12.

[0111] The batteries according to Examples 2 to 12 were subjected to charge / discharge tests in the same manner as in Example 1. The batteries according to Examples 2 to 12 were charged and discharged satisfactorily, as in Example 1.

[0112] <Comparative Examples 1 to 3> (Preparation of solid electrolyte materials) In Comparative Examples 1 to 3, raw material powders of LiCl, YCl3, and ScCl3 were prepared in a dry argon atmosphere in a molar ratio of LiCl:YCl3:ScCl3 = (6-3b):(1-a)b:ab. These raw material powders were milled at 600 rpm for 12 hours using a planetary ball mill. In this way, the solid electrolyte materials of Comparative Examples 1 to 3 were obtained. In other words, no sintering was performed in Comparative Examples 1 to 3.

[0113] (Evaluation of ionic conductivity) The ionic conductivities of the solid electrolyte materials according to Comparative Examples 1 to 3 were measured in the same manner as in Example 1. The measurement results are shown in Table 1. The measurement results are shown in Table 1.

[0114] (X-ray diffraction measurement) The X-ray diffraction patterns of the solid electrolyte materials according to Comparative Examples 1 to 3 were measured in the same manner as in Example 1. Fig. 4 is a graph showing the X-ray diffraction patterns of the solid electrolyte materials according to Comparative Examples 1 to 3. The position and half-width of the peak having the largest intensity within the diffraction angle 2θ range of 27° or more and 36° or less are shown in Table 1.

[0115] [Table 1]

[0116] (Consideration) The solid electrolyte materials according to Examples 1 to 12 had a melting point of 4.4 × 10 -4 The solid electrolyte materials according to Examples 1 to 12 have high ionic conductivity of 100 S / cm or more. In the X-ray diffraction patterns of the solid electrolyte materials according to Examples 1 to 12, the half-width of the peak having the greatest intensity within the diffraction angle 2θ range of 27° to 36° is 0.5° or less. On the other hand, the half-width of the corresponding peak of the solid electrolyte materials according to Comparative Examples 1 to 3 is greater than 0.5°.

[0117] As is clear from a comparison of Examples 2 to 7 with Example 1, when the value of a is 0.35 or more and 1 or less, the solid electrolyte material has higher ionic conductivity. As is clear from a comparison of Examples 5 to 7 with Examples 2 to 4, when the value of a is 0.7 or more and 1 or less, the solid electrolyte material has even higher ionic conductivity. As is clear from a comparison of Examples 6 and 10 to 12 with Example 9, when the value of b is 0.9 or more and 1.1 or less, the solid electrolyte material has higher ionic conductivity.

[0118] The batteries according to Examples 1 to 12 were all charged and discharged at room temperature.

[0119] The solid electrolyte materials according to Examples 1 to 12 do not contain sulfur and therefore do not generate hydrogen sulfide.

[0120] As described above, the solid electrolyte material according to the present disclosure is suitable for providing a battery that does not generate hydrogen sulfide, has high lithium ion conductivity, and can be charged and discharged well. [Industrial Applicability]

[0121] The solid electrolyte material of the present disclosure is used, for example, in an all-solid-state lithium-ion secondary battery. [Explanation of symbols]

[0122] 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 Punch top 302 Frame type 303 Punch bottom 1000 batteries

Claims

1. A solid electrolyte material comprising Li, Sc, and Cl, In the X-ray diffraction pattern of the solid electrolyte material obtained using Cu-Kα radiation, At least two peaks are present in the diffraction angle 2θ range of 27° or more and 36° or less, the half-width of the peak having the largest intensity within the diffraction angle 2θ range of 27° to 36° is 0.5° or less; Represented by the following composition formula (1): Li 6-3b (Y 1-a Sc a ) b Cl 6 ... (1) Here, the following two formulas: 0.35≦a≦1, and 0.7≦b≦1.2 is satisfied; Solid electrolyte material.

2. The formula: 0.7≦a≦1 is satisfied; The solid electrolyte material according to claim 1 .

3. The formula: 0.9≦b≦1.2 is satisfied; The solid electrolyte material according to claim 1 or 2.

4. The half width is 0.15° or more and 0.42° or less. The solid electrolyte material according to claim 1 .

5. positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode; Equipped with 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 4. battery.

Images